FIELD GUIDESource-led reference
Port & Cable

P343 / PC internal / Connector

3-pin PC fan connector / motherboard header

A three-contact PC cooling-fan connection lacks the separate fourth PWM control contact present on a common four-pin PC fan connection.

Also called 3-pin fan header 3 pin PC fan DC fan header three pin fan

Three contacts do not establish automatic speed control: the motherboard must support the correct fan-control method.

Look for

Look for the fan header label on the board and three positions in the fan connector; compare the keyed guide and check the exact fan/board manuals.

Claim inspection dates: 2026-10-09, 2026-10-13, 2026-10-22 · Independent review pending

3-pin PC fan connector / motherboard header: three-quarter view. Computer-generated illustration, not a photograph.

Three-quarter view Computer-generated illustration with prior AI visual review. Not a photograph, measurement or compatibility check. Independent technical and rights review pending.

3-pin PC fan connector / motherboard header: mating face. Computer-generated illustration, not a photograph.

Mating face Computer-generated illustration with prior AI visual review. Not a photograph, measurement or compatibility check. Independent technical and rights review pending.

3-pin PC fan connector / motherboard header: fitted in place. Computer-generated illustration, not a photograph.

Fitted in place Computer-generated illustration with prior AI visual review. Not a photograph, measurement or compatibility check. Independent technical and rights review pending.

3-pin PC fan connector / motherboard header: original recognition drawing, not to scale.

Recognition drawing Original schematic, not to scale. Drawing review pending.

Image inspection / P343

See the view. Check its scope.

2 registered views for this reference. Different part examples are not automatically mates; all remain not to scale and independently unapproved.

Three positions; the exact housing has not been visually qualified here. Textual role concept only; the dedicated three-pin physical illustration remains missing. (private workspace)

P343 / Concept — not physical geometry

3-pin fan — physical image unresolved

Noctua 3-pin fan family (bounded FAQ scope)

Editorial evidence checklist; no component geometry · Concept only

Not to scale. Technical and rights review pending.

Inspect view & provenance (private workspace)
Original typographic comparison of 3-pin and 4-pin fans, USB 2.0 and HD Audio, and 12V RGB and 5V ARGB. No mating, wiring or adapter recommendation. (private workspace)

P343 / Concept — not physical geometry

Same count. Different job.

Editorial comparison of the six existing internal PC forms

Editorial evidence checklist; no component geometry · Concept only

Not to scale. Technical and rights review pending.

Inspect view & provenance (private workspace)

Matching notes / PC control / P343

Will a four-pin header control a three-pin fan?

FIELD NOTES 03

Not necessarily. Noctua describes many compatible connections, but speed regulation depends on the motherboard supporting DC or voltage control.

SOURCE-SUPPORTED LEAD

What the evidence supports

A documented three-pin fan connection may leave the fourth PWM position unused.

INSUFFICIENT MATCHING EVIDENCE

What not to conclude

A four-position header by itself is insufficient proof of adjustable speed for a three-pin fan.

NOT ESTABLISHED

Keep this check open

The actual header’s control mode and device requirements remain unknown without its manual.

Before you choose a part

  1. Read the exact fan and motherboard documentation.
  2. Check whether that header supports DC or voltage control.
  3. Keep fan-control connectors separate from RGB lighting headers.
Evidence for this decision · 3 source-scoped observations

C343A (private workspace) — Noctua explains that its 3-pin fan connector can be used on many 4-pin motherboard fan headers with the fourth PWM position unused.

Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval. S454

C343B (private workspace) — Speed regulation for a three-pin fan depends on a motherboard supporting DC or voltage control; a four-pin header alone is not a speed-control guarantee.

Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval. S454

C344B (private workspace) — Motherboard documentation—not the number of header pins—determines whether its fourth position is implemented as PWM.

Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval. S454 · S455

Manufacturer evidence is not an independent review, wiring assignment or hardware test.

REPAIR FIELD NOTES / Fans and compact power

First verify the exact manufacturer series

Three fan contacts do not create PWM control

It may physically connect to compatible PC motherboard fan headers, with the fourth control position unused, as Noctua documents. Whether the board can vary a three-pin fan’s speed depends on supported DC/voltage control mode in that header; the four-pin outline is not proof.

Avoid: Assuming a four-pin motherboard header always provides PWM speed control to a three-wire fan.

Full source-scoped reading and three practical checks ↗
Qualitative distinction between Micro-Fit · 3.0 mm and Mini-Fit Jr. · 4.2 mm. Nominal pitch cannot validate a power harness. Not to scale, no pinout, no mating approval.
Micro-Fit / Mini-Fit — different Molex familiesNominal pitch cannot validate a power harness. Original conceptual evidence diagram only, not part-number geometry, a live-circuit test, or manufacturer-approved fit.

These notes add editorial context to the original canonical reference; they do not change its claim IDs or prove mating, wiring or polarity.

The useful distinction

Recognize it. Then verify it.

A three-contact PC cooling-fan connection lacks the separate fourth PWM control contact present on a common four-pin PC fan connection. [C343A]

Speed regulation for a three-pin fan depends on a motherboard supporting DC or voltage control; a four-pin header alone is not a speed-control guarantee. [C343B]

For Noctua’s described 3-pin fan connection to a 4-pin header, the separate PWM position remains unused. [C343C]

Noctua says automatic control can depend on motherboard voltage regulation; pulsing power is not equivalent to lowering the supply voltage. [C343D]

Noctua documents fans across 5V, 12V and 24V families; a contact-count label is not a voltage identification. [C343E]

The named ASRock H81M CHA_FAN2 and PWR_FAN1 diagrams show three positions in one inline row. The manual gives no pitch or exact header component part. [C343W]

PC internals · a documented check

My fan fits the header. Why is speed control still uncertain?

The control mode matters. In Noctua’s described three-pin-to-four-pin connection, the fourth PWM position is unused; regulation depends on the motherboard’s voltage-control support. Contact count is also not a fan-voltage label. C343A · C343B · C343C · C343E

What the documentation establishes—and what still needs checking
CheckDocumented distinctionBoundary
Three-pin exampleThe separate PWM position is unused in Noctua’s described connection. C343C · C343BFit alone is not automatic speed control.
Control modeThree-pin regulation depends on supported DC/voltage control. C343B · C343DPulsing the supply is not the same as reducing its voltage.
Named board defaultsB550-A PRO lists Auto for CPU_FAN1, PWM for PUMP_FAN1 and DC for SYS_FAN1–6. C344EThose are this manual’s defaults, not the present BIOS state of an unknown board.
Voltage and roleNoctua documents 5V, 12V and 24V families; fan-cable and PCB-header roles differ. C343E · C344CDo not identify voltage or component sex from “three-pin” or “four-pin” alone.

Check these next

  1. Read the fan model’s voltage and the exact header’s electrical limits before considering physical fit.
  2. Find that header’s supported control mode in the board manual and its actual BIOS setting.
  3. Keep a separate lighting lead out of the fan-motor comparison.

Keep this limit: The three-pin fan’s exact physical-study gap remains open. This reference does not certify proprietary headers, splitters or the number of fans that one output can power. C343B · C343E

Source-scoped identification facts

Each value retains its exact example, role and measurement axis. Facts from different parts must not be combined into an invented component.

Documented examples; not a mating drawing or compatibility approval
Positions / cavity span3 (Noctua NF-A8 FLX fan assembly)S835Source-scoped examples are separate; select the exact variant and measured axis. Noctua NF-A8 FLX fan assembly. Named primary-source example only. Identification facts do not certify mating, electrical compatibility, fabrication or powered use.
Contact rows1 (ASRock H81M CHA_FAN2/PWR_FAN1)S834Current primary-source scoped values; named examples remain separate and unknowns are not inferred from illustrations. Exact equipment variant ASRock H81M CHA_FAN2/PWR_FAN1, manual contact arrangement only; no generic component family geometry. Quantity context: Source manual contact row.
Connector role3-pin fan cable connector (Noctua NF-A8 FLX fan assembly)S835Source-scoped examples are separate; select the exact variant and measured axis. Noctua NF-A8 FLX fan assembly. Named primary-source example only. Identification facts do not certify mating, electrical compatibility, fabrication or powered use.
Shell / formConnector type listed as 2510-3PIN (or equal) (Noctua NF-A8 FLX fan assembly)S835Source-scoped examples are separate; select the exact variant and measured axis. Noctua NF-A8 FLX fan assembly. Named primary-source example only. Identification facts do not certify mating, electrical compatibility, fabrication or powered use.
Exact part / implementationNF-A8 FLX (fan assembly connector implementation) (Noctua NF-A8 FLX fan assembly)S835Source-scoped examples are separate; select the exact variant and measured axis. Noctua NF-A8 FLX fan assembly. Named primary-source example only. Identification facts do not certify mating, electrical compatibility, fabrication or powered use.

Not recorded: Nominal contacts, Populated contacts, Contact pitch, Dimensions / axis, Contact gender / arrangement, Mounting, Coupling / latch, Keying / polarization, Manufacturer, Series, Recorded markings, View convention. Unknown fields stay unknown; illustrations supply no measurements or pin assignments.

Recorded variant and source limits
  • Check the exact device manual before wiring or applying power.
  • ASRock H81M 3-pin CPU_FAN2 / CHA_FAN2 / PWR_FAN1 board headers: Diagram labels GND, +12V and FAN_SPEED in order from the end next to the locking ramp; contact numbers are not printed.
  • Noctua NF-A8 FLX: Numbered fan-cable contacts in the Noctua NF-A8 FLX specification; left/right face and wire-entry orientation remain UNVERIFIED.
  • Noctua NF-A8 5V: Numbered fan-cable contacts in the Noctua NF-A8 5V specification; left/right face and wire-entry orientation remain UNVERIFIED.
Report a correction to these facts →

Bounded facts, visible unknowns

Specifications and limits

3-pin PC fan connector / motherboard header facts and limitations
Common PC formThree contact positions; voltage and control must be checked on exact equipment [C343A]
Role and recognition scopeFan cable end / counterpart header — Noctua 3-pin fan family (bounded FAQ scope). Original qualitative study only; no wiring or fit approval. [C343C] [C343D] [C343E]
Mechanical dimensionsOnly manufacturer-described nominal family/footprint pitch is quoted in sourced text; no measured fabrication/tolerance drawing independently approved.
Engineering pinoutSource-checked engineering profile available; independent review pending. Open engineering profile →
Verified device listNot included. Check exact device and accessory documentation.
A boundary, not an omission to guess around.

Power down and disconnect the system before inspecting headers; consult the board manual for CPU_FAN/SYS_FAN location. Confirm fan model, voltage and the motherboard header’s permitted current; do not infer a rating from the contact count. Check whether the motherboard controls speed by DC/voltage adjustment; never force a different keyed plug.

Before you connect

What to check

  1. Power down and disconnect the system before inspecting headers; consult the board manual for CPU_FAN/SYS_FAN location.
  2. Confirm fan model, voltage and the motherboard header’s permitted current; do not infer a rating from the contact count.
  3. Check whether the motherboard controls speed by DC/voltage adjustment; never force a different keyed plug.
Trace a supported connection class →

Pins & wiring

Pinout

Choose the exact wiring. Pin numbers follow its stated view; a schematic does not establish physical positions. Check your exact device before wiring.

What the status labels mean
Confirmed
Recorded research passes agree within this variant; this is not independent human review or hardware validation.
Single source
Only one underlying document, or one pass, supports this assignment.
Device-specific
Supported for the named equipment or wiring only. Check your device’s manual.
Unverified
Missing or conflicting evidence. Do not wire from this row.
Not connected
The source explicitly says NC, no contact or no pin for this wiring.
Wiring variant

ASRock H81M 3-pin CPU_FAN2 / CHA_FAN2 / PWR_FAN1 board headers

Device-specific wiring. Check your device’s manual before connecting or applying power.

View and evidence limits

Diagram labels GND, +12V and FAN_SPEED in order from the end next to the locking ramp; contact numbers are not printed.

  • P343 3-pin fan — **Partial**: numbered evidence in B only — A's ASRock H81M diagram labels positions but no numbers, so its three rows stay unverified. B's numbered Noctua NF-A8 FLX and NF-A8 5V specifications give 1 ground, 2 Vcc, 3 RPM. These are named fan-cable variants with different supply voltages, not an independently confirmed universal motherboard map.
  • The same manual says a 3-pin CPU fan plugged into the 4-pin CPU_FAN1 goes on 'Pin 1-3', but the 4-pin diagram also does not print numbers.
  • Signal order is shown but contact numbers 1-3 are not printed in the ASRock diagrams, so the number-to-signal mapping is unverified.
  • Intel's 4-Wire PWM Controlled Fans specification (rev 1.2/1.3) was not found on an Intel host; only third-party mirrors were located and not used. A Noctua white paper on noctua.at was blocked by a bot checkpoint / HTTP 429.
3-pin PC fan engineering referenceDiagram labels GND, +12V and FAN_SPEED in order from the end next to the locking ramp; contact numbers are not printed.SCHEMATIC · physical positions unconfirmedNot to scale · check the named wiring and device manual1: Not confirmed (unverified)12: Not confirmed (unverified)23: Not confirmed (unverified)3powergrounddataConfigshieldNCUnknown
Schematic only · physical contact positions unconfirmed. Original drawing · not to scale. Scroll sideways if needed.

Not yet independently confirmed. No settled pin table is available for this wiring.

Sources (1)
  • S834 · ASRock · H81M User Manual

    Version 1.1, published October 2014 · Section 'Onboard Headers and Connectors', Chassis and Power Fan Connectors (3-pin CHA_FAN2, 3-pin PWR_FAN1) printed p. 25, and CPU Fan Connectors (3-pin CPU_FAN2) printed p. 26

Noctua NF-A8 FLX

Device-specific wiring. Check your device’s manual before connecting or applying power.

View and evidence limits

Numbered fan-cable contacts in the Noctua NF-A8 FLX specification; left/right face and wire-entry orientation remain UNVERIFIED.

  • P343 3-pin fan — **Partial**: numbered evidence in B only — A's ASRock H81M diagram labels positions but no numbers, so its three rows stay unverified. B's numbered Noctua NF-A8 FLX and NF-A8 5V specifications give 1 ground, 2 Vcc, 3 RPM. These are named fan-cable variants with different supply voltages, not an independently confirmed universal motherboard map.
  • No separate fourth PWM contact.
  • Twelve-volt model; do not assume all three-pin fans use the same voltage.
  • Only named fan cables are mapped. Generic motherboard DC behavior, other voltages/models and a physical face/rear numeric layout are unverified.
3-pin PC fan engineering referenceNumbered fan-cable contacts in the Noctua NF-A8 FLX specification; left/right face and wire-entry orientation remain UNVERIFIED.SCHEMATIC · physical positions unconfirmedNot to scale · check the named wiring and device manual1: Ground (GND), black (device_specific)12: Voltage (Vcc), red (device_specific)23: RPM Signal, yellow (device_specific)3powergrounddataConfigshieldNCUnknown
Schematic only · physical contact positions unconfirmed. Original drawing · not to scale. Scroll sideways if needed.
Noctua NF-A8 FLX — source-scoped contact map
PinSignalWhat it doesStatus
1Ground (GND), blackGround reference and return.Device-specific
Sources
2Voltage (Vcc), redPower connection (Voltage (Vcc), red). Check the specified supply.Device-specific
Sources
3RPM Signal, yellowWire colour for this termination: RPM Signal, yellow.Device-specific
Sources
Sources (1)
  • S835 · Noctua · NF-A8 FLX — Specifications

    Undated live manufacturer specification page; accessed 2026-10-21 · Specifications > Extended specifications > Electrical specifications, Rated voltage and Pin configuration rows; Mechanical specifications > Connector type

Noctua NF-A8 5V

Device-specific wiring. Check your device’s manual before connecting or applying power.

View and evidence limits

Numbered fan-cable contacts in the Noctua NF-A8 5V specification; left/right face and wire-entry orientation remain UNVERIFIED.

  • P343 3-pin fan — **Partial**: numbered evidence in B only — A's ASRock H81M diagram labels positions but no numbers, so its three rows stay unverified. B's numbered Noctua NF-A8 FLX and NF-A8 5V specifications give 1 ground, 2 Vcc, 3 RPM. These are named fan-cable variants with different supply voltages, not an independently confirmed universal motherboard map.
  • No separate fourth PWM contact.
  • Noctua explicitly marks the 5 V model as not for use in PCs.
  • Only named fan cables are mapped. Generic motherboard DC behavior, other voltages/models and a physical face/rear numeric layout are unverified.
3-pin PC fan engineering referenceNumbered fan-cable contacts in the Noctua NF-A8 5V specification; left/right face and wire-entry orientation remain UNVERIFIED.SCHEMATIC · physical positions unconfirmedNot to scale · check the named wiring and device manual1: Ground (GND), black (device_specific)12: Voltage (Vcc), red (device_specific)23: RPM Signal, yellow (device_specific)3powergrounddataConfigshieldNCUnknown
Schematic only · physical contact positions unconfirmed. Original drawing · not to scale. Scroll sideways if needed.
Noctua NF-A8 5V — source-scoped contact map
PinSignalWhat it doesStatus
1Ground (GND), blackGround reference and return.Device-specific
Sources
2Voltage (Vcc), redPower connection (Voltage (Vcc), red). Check the specified supply.Device-specific
Sources
3RPM Signal, yellowWire colour for this termination: RPM Signal, yellow.Device-specific
Sources
Sources (1)
  • S836 · Noctua · NF-A8 5V — Specifications

    Undated live manufacturer specification page; accessed 2026-10-21 · Specifications > Extended specifications > Electrical specifications, Rated voltage and Pin configuration rows; Mechanical specifications > Connector type

Important boundary

This reference establishes only the specific manufacturer-documented family and example noted in the sources. It does not verify an arbitrary mating pair, cable orientation, electrical rating or device combination. Stop and consult original documents for the exact products.

Source-scoped V142 recognition check

Noctua 3-pin fan family (bounded FAQ scope). Three positions; the exact housing has not been visually qualified here. Fan control and voltage still need separate evidence. Read the fan voltage label and the exact board fan-control mode; retain the physical-image request. Still unresolved: Exact 3-pin housing, key profile, installed header and permitted load. See the internal-header field reference for source revision, observation limits and the comparison.

Your next step

Move from the form to the requirement.

Read the engineering reference Source-scoped details, orientation and explicit unknowns.Work through a connection Choose your task before deciding on a cable.Explore this evidence trail Inspect the claims and their dependencies. (private workspace)

The source trail

Evidence for this page

AI-assisted inspection is not independent engineering review. Source scope and access limitations are disclosed below. Procedural checklists are editorial requirements, not hardware measurements.

Back to first citation ↑
C343ASource checked · pending review

Noctua explains that its 3-pin fan connector can be used on many 4-pin motherboard fan headers with the fourth PWM position unused.

Noctua · Noctua 3-pin and 4-pin motherboard fan FAQ ↗

Locator: 3-pin fan on 4-pin PWM header; 4-pin fan on 3-pin header; PWM versus DC control
Access: public page. Fan color, connector shape and header modes vary; not a universal polarity or current-rating certificate.

S454: full source recordInspect review dependencies → (private workspace)

Claim scope: Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval.. Next review due 2027-01-07.

Back to first citation ↑
C343BSource checked · pending review

Speed regulation for a three-pin fan depends on a motherboard supporting DC or voltage control; a four-pin header alone is not a speed-control guarantee.

Noctua · Noctua 3-pin and 4-pin motherboard fan FAQ ↗

Locator: 3-pin fan on 4-pin PWM header; 4-pin fan on 3-pin header; PWM versus DC control
Access: public page. Fan color, connector shape and header modes vary; not a universal polarity or current-rating certificate.

S454: full source recordInspect review dependencies → (private workspace)

Claim scope: Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval.. Next review due 2027-01-07.

Back to first citation ↑
C343CSource checked · pending review

For Noctua’s described 3-pin fan connection to a 4-pin header, the separate PWM position remains unused.

Noctua · Noctua 3-pin and 4-pin motherboard fan FAQ ↗

Locator: 3-pin fan on 4-pin PWM header; 4-pin fan on 3-pin header; PWM versus DC control
Access: public page. Fan color, connector shape and header modes vary; not a universal polarity or current-rating certificate.

S454: full source recordInspect review dependencies → (private workspace)

Claim scope: V142: named MSI B550-A PRO manual version 6.0 (2024/02) or explicitly identified Noctua family only. Role/recognition evidence, not generic wiring, safe mating, pinout approval, dimensions or installed-device certification.. Next review due 2027-01-11.

Back to first citation ↑
C343DSource checked · pending review

Noctua says automatic control can depend on motherboard voltage regulation; pulsing power is not equivalent to lowering the supply voltage.

Noctua · Noctua 3-pin and 4-pin motherboard fan FAQ ↗

Locator: 3-pin fan on 4-pin PWM header; 4-pin fan on 3-pin header; PWM versus DC control
Access: public page. Fan color, connector shape and header modes vary; not a universal polarity or current-rating certificate.

S454: full source recordInspect review dependencies → (private workspace)

Claim scope: V142: named MSI B550-A PRO manual version 6.0 (2024/02) or explicitly identified Noctua family only. Role/recognition evidence, not generic wiring, safe mating, pinout approval, dimensions or installed-device certification.. Next review due 2027-01-11.

Back to first citation ↑
C343ESource checked · pending review

Noctua documents fans across 5V, 12V and 24V families; a contact-count label is not a voltage identification.

Noctua · Noctua FAQ — fan pin-configuration and voltage families ↗

Locator: Main FAQ prose reviewed 2026-10-13. Inline fan drawings could not be visually acquired in this run; text-only observation, no image qualification.
Access: public page. Observed document is not a real-hardware inspection, installed-device approval, wiring guide, current revision guarantee or manufacturing specification.

S593: full source recordInspect review dependencies → (private workspace)

Claim scope: V142: named MSI B550-A PRO manual version 6.0 (2024/02) or explicitly identified Noctua family only. Role/recognition evidence, not generic wiring, safe mating, pinout approval, dimensions or installed-device certification.. Next review due 2027-01-11.

Back to first citation ↑
C343WSource checked · pending review

The named ASRock H81M CHA_FAN2 and PWR_FAN1 diagrams show three positions in one inline row. The manual gives no pitch or exact header component part.

ASRock · H81M User Manual ↗

Locator: Section 'Onboard Headers and Connectors', Chassis and Power Fan Connectors (3-pin CHA_FAN2, 3-pin PWR_FAN1) printed p. 25, and CPU Fan Connectors (3-pin CPU_FAN2) printed p. 26
Access: public pdf text. Source scope and unresolved evidence are preserved in the engineering variant.

S834: full source recordInspect review dependencies → (private workspace)

Claim scope: Exact equipment variant ASRock H81M CHA_FAN2/PWR_FAN1, manual contact arrangement only; no generic component family geometry.. Next review due 2027-01-20.

Suggest a correction to this field note →

Put this field note to work.

Add to discovery trayRecord an unsaved candidate (private workspace)

Candidate selection does not confirm the identity or capabilities of your physical item.

Evidence behind this page

Scope first. Source second. Approval separate.

3 linked sources · 6 scoped claims · 0 sources with inspection/access flags.

Page scope: evidence_first_v103_pc_and_jst

Assessment 2026-10-22 · earliest scheduled source review 2027-01-07. This is a recorded-date assessment, not a live source check. Page-level independent review is not established by this panel.

Inspect 3 source scopes, access limits and dates

S454 · Noctua 3-pin and 4-pin motherboard fan FAQ

Noctua · Unclassified publisher domain · inspected 2026-10-09 · due 2027-01-07

Within inspection window

Scoped support: Fan-family contact-count and conditional motherboard control; Noctua examples only.

Not established / limitations: Fan color, connector shape and header modes vary; not a universal polarity or current-rating certificate.

Locator: 3-pin fan on 4-pin PWM header; 4-pin fan on 3-pin header; PWM versus DC control

S593 · Noctua FAQ — fan pin-configuration and voltage families

Noctua · Unclassified publisher domain · inspected 2026-10-13 · due 2027-01-11

Within inspection window

Scoped support: Noctua fan family voltage range; no wire-colour table or source image promoted.

Not established / limitations: Observed document is not a real-hardware inspection, installed-device approval, wiring guide, current revision guarantee or manufacturing specification.

Locator: Main FAQ prose reviewed 2026-10-13. Inline fan drawings could not be visually acquired in this run; text-only observation, no image qualification.

S834 · H81M User Manual

ASRock · Unclassified publisher domain · inspected 2026-10-21 · due 2027-01-19

Within inspection window

Scoped support: Exact named pinout variant only; not capability or compatibility approval.

Not established / limitations: Source scope and unresolved evidence are preserved in the engineering variant.

Locator: Section 'Onboard Headers and Connectors', Chassis and Power Fan Connectors (3-pin CHA_FAN2, 3-pin PWR_FAN1) printed p. 25, and CPU Fan Connectors (3-pin CPU_FAN2) printed p. 26

Trace 6 claims to their source records

C343A · P343

Noctua explains that its 3-pin fan connector can be used on many 4-pin motherboard fan headers with the fourth PWM position unused.

Claim scope: Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval.

Source links: S454 · Evidence trail → (private workspace)

C343B · P343

Speed regulation for a three-pin fan depends on a motherboard supporting DC or voltage control; a four-pin header alone is not a speed-control guarantee.

Claim scope: Manufacturer-specific family/physical identification only. No inferred device wiring, mating verification or installation approval.

Source links: S454 · Evidence trail → (private workspace)

C343C · P343

For Noctua’s described 3-pin fan connection to a 4-pin header, the separate PWM position remains unused.

Claim scope: V142: named MSI B550-A PRO manual version 6.0 (2024/02) or explicitly identified Noctua family only. Role/recognition evidence, not generic wiring, safe mating, pinout approval, dimensions or installed-device certification.

Source links: S454 · Evidence trail → (private workspace)

C343D · P343

Noctua says automatic control can depend on motherboard voltage regulation; pulsing power is not equivalent to lowering the supply voltage.

Claim scope: V142: named MSI B550-A PRO manual version 6.0 (2024/02) or explicitly identified Noctua family only. Role/recognition evidence, not generic wiring, safe mating, pinout approval, dimensions or installed-device certification.

Source links: S454 · Evidence trail → (private workspace)

C343E · P343

Noctua documents fans across 5V, 12V and 24V families; a contact-count label is not a voltage identification.

Claim scope: V142: named MSI B550-A PRO manual version 6.0 (2024/02) or explicitly identified Noctua family only. Role/recognition evidence, not generic wiring, safe mating, pinout approval, dimensions or installed-device certification.

Source links: S593 · Evidence trail → (private workspace)

C343W · P343

The named ASRock H81M CHA_FAN2 and PWR_FAN1 diagrams show three positions in one inline row. The manual gives no pitch or exact header component part.

Claim scope: Exact equipment variant ASRock H81M CHA_FAN2/PWR_FAN1, manual contact arrangement only; no generic component family geometry.

Source links: S834 · Evidence trail → (private workspace)

Prepare this page for review → (private workspace)Read the evidence method →

Recorded evidence only. An inspection date, publisher label, source link or generated packet is not independent technical review, hardware testing, fabrication approval or a compatibility verdict.