What size screw does PSU internals & fan grilles use?

M3 × 5–8 mm for internal PSU assembly (PSU-to-case screws are larger).

How long are the screws in PSU internals & fan grilles?

The records range from 5 to 8 mm depending on the position, so match each screw to its own hole.

What is the thread pitch of an M3 screw?

0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.

What screwdriver do I need for PSU internals & fan grilles?

The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.

Can I use an imperial screw instead of M3?

No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.

Where can I buy replacement screws for PSU internals & fan grilles?

TechSpareWarehouse (our own store) lists M3 x 5mm, M3 x 6mm and M3 x 8mm, which match lengths in the records above.

PSU internals & fan grilles screw size

M3 · 5 to 8 mm long

PSU internals & fan grilles takes M3 metric screws in lengths from 5 to 8 mm.

Where it is used: internal PSU assembly (PSU-to-case screws are larger).

This entry is marked reported and comes from shuntool.com.

M3 means a 3 mm nominal diameter with a 0.5 mm thread pitch. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.

PSU internals & fan grilles screw specifications

One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.

Thread	Length	Pitch	Head	Drive	Where it goes	Status
M3	5–8 mm	0.5 mm	not stated	not stated	internal PSU assembly (PSU-to-case screws are larger)	Reported

Fitment records and sources

M35-8mmreported

internal PSU assembly (PSU-to-case screws are larger)

pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10

Source

How to check the screw before you buy

If several screws hold the same part, check that they are all the same length before assuming they are.
Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
The records span 5–8 mm, which means different positions take different lengths — match each hole to its own screw.
Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.

Common mix-ups with M3

Pond/aquarium equipment manuals aimed at consumers rarely specify exact thread pitch or length for internal fasteners, since these are considered non-user-serviceable; distributor-level assembly/service manuals (e.g., Maytronics internal documents) are a better source than end-user guides.
M3 (3.0mm, 0.5mm pitch) is not #6-32 UNC (~3.5mm) — they look identical and cross-thread, the single most common PC-building mistake.

Pitch gauge · Screw size finder · Torque guide

Buy these screws at TechSpare Warehouse

In stock and shipped from South Carolina. Our black screws are Phillips wafer head (low profile); match the head style and length to the original before you order.

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The same screw also fits

Devices whose records share a thread with PSU internals & fan grilles, closest length match first.

Kern PFB precision balance internal hardware also M3 × 6–8 mm
Commodore Amiga 500/600/1200 desktop case also M3 × 6 mm
Wimberley AP-503 replacement foot also M3 × 6 mm
Amiga 500 rear/front case screws (Retro32 replacement set) also M3 × 8 mm
RED Digital Cinema Matte Box Cage & Side Flags Kit also M3 × 6 mm
Kenwood TK-8302 transceiver also M3 × 8 mm
Eschmann LS5 / SES2555 autoclave also M3 × 8 mm
2020 aluminium extrusion T-nuts also M3 × 6–8 mm

Questions about PSU internals & fan grilles screws

What size screw does PSU internals & fan grilles use?: M3 × 5–8 mm for internal PSU assembly (PSU-to-case screws are larger).
How long are the screws in PSU internals & fan grilles?: The records range from 5 to 8 mm depending on the position, so match each screw to its own hole.
What is the thread pitch of an M3 screw?: 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
What screwdriver do I need for PSU internals & fan grilles?: The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
Can I use an imperial screw instead of M3?: No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.
Where can I buy replacement screws for PSU internals & fan grilles?: TechSpareWarehouse (our own store) lists M3 x 5mm, M3 x 6mm and M3 x 8mm, which match lengths in the records above.

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