Motherboard Standoff Screws: Sizes and What You Need

Motherboard standoff screws are threaded metal spacers that elevate a motherboard above the PC case tray, preventing electrical shorts and securing the board in place.

Last updated: July 2026

Quick Answer: What Are Motherboard Standoff Screws?

Motherboard standoff screws are two-part fasteners: a hex-bodied spacer (the standoff) that threads into the case tray, and a smaller screw that passes through the motherboard hole into the standoff’s top thread. Together they lift the PCB roughly 6.35mm off the metal case floor. The dominant thread standard for consumer desktop builds is 6-32 UNC, and they come with the PC case, not the motherboard.

Most builders only think about standoffs once, when something goes wrong. Either they’re missing one, they’ve got an extra one in the wrong place, or they’ve lost the tiny tool needed to seat them. Getting this right is one of those details that separates a clean, stable build from a board that won’t POST on first boot. This guide covers exact sizes, thread specs, materials, tools, and every mistake worth avoiding.

What Are Motherboard Standoff Screws?

Why Standoffs Matter in a PC Build

A motherboard’s underside is covered in exposed solder points, trace pathways, and component legs. Set that board directly onto a bare steel case tray and you’ll bridge dozens of circuits the moment it powers on. Not great. Standoffs create the physical gap, typically 6.35mm for ATX builds, that keeps all of that isolated from the conductive metal below.

Beyond preventing shorts, standoffs serve two other functions builders often overlook. First, they provide a grounding path: brass standoffs create a controlled electrical connection between the board and the case chassis, which helps with EMI shielding. Second, they’re structural. A motherboard loaded with a heavy GPU, a beefy CPU cooler, and multiple PCIe cards needs solid anchor points distributed across its mounting holes. Without enough standoffs, the PCB flexes under that weight, which stresses traces and solder joints over time.

ATX boards have up to 9 mounting holes. Micro-ATX typically uses 6. Mini-ITX uses 4. Each one needs a standoff beneath it, positioned precisely to match. One standoff in the wrong place is as damaging as a missing one.

Do Standoff Screws Come With the Motherboard?

No. Standoffs come with the PC case. This trips up first-time builders constantly, especially after they open the motherboard box looking for them. The motherboard box contains SATA cables, the I/O shield, a manual, and sometimes an M.2 mounting screw, but not the standoffs you need to mount the board itself. For a full breakdown of what M.2 fasteners look like and how they differ, the M.2 screw guide covering sizes and types covers that territory in detail. Using a screw that’s too long is a common error that causes the fastener to spin endlessly without catching, it bottoms out in the standoff’s threaded bore before clamping the board down. That thread on Tom’s Hardware forums is worth bookmarking if you’re sourcing replacement screws.

Included With	What You Get
PC Case	Standoffs (pre-installed or bagged), mounting screws, sometimes a combo tool
Motherboard Box	SATA cables, I/O shield, manual, sometimes an M.2 screw and standoff
Neither (buy separately)	Extra standoffs, replacement screws, mixed standoff kits

Many modern mid-towers from Fractal, Corsair, and NZXT come with standoffs pre-installed for the ATX layout. That’s convenient until you’re building with a Micro-ATX or Mini-ITX board, those hole positions often don’t match the pre-installed set. You’ll need to move or add standoffs manually. Check your case manual before assuming the pre-installed positions are correct for your form factor.

Motherboard Standoff Screw Sizes: The Exact Specs You Need

The Two Standard Thread Types

Consumer PC building in North America is almost entirely standardized around 6-32 UNC. That’s a #6 diameter coarse-thread screw at 32 threads per inch. M3 is the metric equivalent, common in European-market cases and server hardware. They are not interchangeable, forcing one into the other strips the threads.

Spec	6-32 UNC	M3
Thread Diameter	0.138 in (3.51mm)	3.0mm
Thread Pitch	32 threads per inch	0.5mm
Common Use	Most ATX/mATX/ITX desktop cases in North America	European cases, server boards, M.2 drives
Head/Socket Size	1/4 inch hex (6.35mm)	5mm hex
Standard Standoff Height	6.35mm (1/4 inch)	6mm

One thing that confuses builders: the standoff body threads into the case tray and the mounting screw threads into the top of the standoff. These two interfaces can technically use different thread standards, though in practice they’re the same on any properly paired case hardware. Case manufacturers sometimes publish their own screw and standoff reference diagrams in product documentation or manuals, worth checking if you’re unsure which screw goes where in your specific case.

Do All Motherboards Use the Same Standoff Screws?

Yes, with one exception. Every ATX, Micro-ATX, and Mini-ITX motherboard uses 6-32 UNC mounting holes as defined by the ATX form factor specification. The hole positions differ between form factors, but the thread standard is consistent. Whether you’re mounting a budget B760 board or a flagship X870E for a Ryzen 9 9950X3D build, the mounting hardware is the same.

The exception: proprietary OEM machines. Some Dell and HP prebuilt systems use non-standard board layouts and mounting patterns. If you’re transplanting an OEM board into a new case or replacing hardware in a prebuilt, verify the hole positions against your case before assuming the standoffs will line up.

Standoff Height, Does It Matter?

Yes. The ATX spec calls for 6.35mm. If you use shorter standoffs, the I/O shield won’t align with the rear panel cutout on your case. If you use taller ones (9.5mm or 11mm, which show up in custom modding builds), the rear I/O area will be recessed into the case or protruding, neither is acceptable in a standard build. Stick with 6.35mm for any ATX/mATX/Mini-ITX build in a standard case. The custom heights only make sense if you’re working in a test bench or open-frame chassis that specifically calls for them.

Types of Motherboard Standoffs by Material

Brass Standoffs (Most Common)

Brass is the default material in virtually every consumer PC case, and for good reason. It’s electrically conductive (which supports the grounding function), highly resistant to corrosion, and has thread durability that holds up to repeated removal and reinstallation over multiple builds. Each standoff weighs roughly 1 to 2 grams. If your case came with brass standoffs and you haven’t stripped them, there’s no reason to replace them.

Steel Standoffs

Stronger than brass on paper, but uncoated steel rusts. Steel standoffs show up in server chassis and some budget cases where cost drives the material choice. They work fine, but in a build that sits in a humid room or gets opened infrequently, they can develop surface rust that makes removal annoying. Zinc-plated or nickel-coated steel versions handle this better.

Nylon/Plastic Standoffs

Non-conductive. That’s the key characteristic. Plastic standoffs don’t ground the board to the case, which means they’re not a substitute for brass or steel in a standard build. Where they do make sense: mounting secondary PCBs like ARGB controllers, fan hubs, or small expansion boards inside the case where you want electrical isolation. Don’t use them as the primary standoffs for your motherboard.

Aluminum Standoffs

Lightweight and clean-looking, aluminum standoffs appear in custom modding builds and open-frame test benches. They’re less common in stock case hardware. Thread durability is lower than brass, so they’re better suited to permanent or semi-permanent installations where you’re not repeatedly pulling the board in and out.

Material	Conductive	Corrosion Resistance	Best Use Case
Brass	Yes	Excellent	All standard consumer builds
Steel (coated)	Yes	Good (varies by coating)	Server chassis, budget cases
Nylon/Plastic	No	Excellent	Secondary PCB mounting, isolation
Aluminum	Yes	Good	Custom mods, open-frame benches

Tools You Need for Installing Motherboard Standoffs

The Motherboard Standoff Tool (Combo Driver)

The dedicated standoff tool is a two-ended driver: one end is a 1/4-inch hex socket that fits over the standoff body, the other end is a Phillips head for the mounting screw. Both tasks handled by one tool. It’s not glamorous, but it’s the right tool for the job.

Most mid-range and premium cases include this in the accessory bag. Check before buying, it’s often taped to a cardboard insert inside the case packaging and easy to overlook. If your case didn’t include one, standalone versions run $3 to $8. If you’re building PCs regularly, a full PC toolkit set in the $20 to $40 range will include this along with anti-static tools, spudgers, and a proper Phillips #2 driver.

The socket size you need for 6-32 UNC standoffs is a 1/4-inch (6.35mm) hex socket. That’s the spec. Write it down before you go shopping.

Can You Use a Regular Screwdriver for Standoffs?

For the mounting screws (the small Phillips screws that go through the motherboard hole into the standoff), yes, a Phillips #2 screwdriver works perfectly. For the standoff body itself, a regular screwdriver won’t engage the hex head. You need a hex socket. Needle-nose pliers work in a pinch, but you risk slipping and scratching the motherboard or rounding the standoff’s hex faces. If you’re in a situation where pliers are your only option, go slow and grip firmly at the base.

Torque Guidance, How Tight Should Motherboard Standoff Screws Be?

The ATX specification doesn’t publish a torque value for motherboard mounting screws. Finger-tight plus approximately a quarter-turn with a tool is the practical rule. That’s enough to create firm contact without stressing the PCB.

Over-tightening is a real failure mode. It doesn’t always break the board immediately, more often it creates micro-cracks in solder joints near the mounting holes that cause intermittent instability weeks or months later. Under-tightening is also bad: the board can shift slightly under load, degrading ground contact and potentially working a screw loose over time. Snug with slight resistance. That’s the target.

How to Install Motherboard Standoffs: Step-by-Step

1. Identify your motherboard form factor, ATX, Micro-ATX, or Mini-ITX, and locate the corresponding hole layout in your case manual. Most manuals include a diagram with labeled positions.
2. Install the I/O shield first, snap it into the rear panel cutout before any standoffs go in. Forgetting this means a full board removal to fix it. Common mistake. Do it first.
3. Position standoffs in the correct holes, match the case tray positions to your motherboard’s hole pattern. ATX uses up to 9 holes; Micro-ATX typically 6; Mini-ITX uses 4.
4. Thread standoffs into the tray using your 1/4-inch hex socket or combo standoff tool. Clockwise until snug. Don’t overtighten, you’re threading into a steel or aluminum tray.
5. Audit the standoff positions, physically verify that every installed standoff aligns with an actual hole in your motherboard. A standoff under a non-hole area will contact the PCB and cause a short.
6. Lower the motherboard onto the standoffs, align all the mounting holes before letting the board rest on them. The I/O shield tabs should press into the ports as the board seats.
7. Finger-tighten all mounting screws first, working across the board before committing any of them. This lets the board settle into its final position before you lock it down.
8. Final snug pass in a cross pattern, like torquing lug nuts on a wheel. This ensures even pressure distribution across the PCB.

If you’re new to seating a processor before dropping the board into the case, the step-by-step CPU installation guide walks through that process in detail and covers what to verify before the board goes in.

Common Standoff Mistakes and How to Avoid Them

• Extra standoff touching the PCB: If a standoff is installed under a solid (non-hole) area of the board, it bridges a ground point across a non-ground trace. The board often won’t POST. The fix is removing the board, auditing every standoff position, and reinstalling.
• Missing standoffs causing board sag: A heavy GPU, a 360mm AIO, and multiple NVMe drives add real weight to a motherboard. Unsupported areas of the PCB flex over time. That flex stresses traces.
• Wrong thread type: Threading an M3 screw into a 6-32 standoff, or vice versa, strips the softer thread almost immediately. Know which standard your case uses before sourcing replacements. The diameter difference is small enough that the screw will start to engage and feel like it’s working until it doesn’t.
• Forgetting the I/O shield: Mentioned in the install steps, worth repeating here. Requires a complete board removal to fix. Do it first. Every time.
• Over-tightening: Cracked solder joints near mounting holes don’t always show up immediately. The board may boot and run normally for weeks before the instability starts. There’s no recovery from cracked traces, just prevention.
• Using standoffs of the wrong height: I/O shield misalignment is the immediate symptom. The rear ports won’t sit flush with the case cutout, and the metal tabs on the shield will press against connectors at odd angles.

Where to Buy Replacement Motherboard Standoffs

You’ll need replacement standoffs when your case came with the wrong size pre-installed, when you’ve lost hardware between builds, or when you’re doing a custom mod that requires a different height. Search specifically for “6-32 brass standoff M/F 6.35mm” to get the right size for consumer ATX builds. Mixed kits in the 50 to 100 piece range (around $8 to $15) are the practical choice, they cover multiple builds and usually include a variety of complementary screws.

For in-person purchases, Micro Center stocks standoffs in their PC hardware accessories section. B&H Photo also carries them online. For Amazon orders, read reviews carefully and look for kits that mention accurate thread gauging, unbranded bulk kits occasionally have sloppy thread tolerances that strip easily. The PC Form Factors working group publishes the ATX and microATX dimensional standards these components must meet, which is useful context when evaluating third-party kits.

FAQ, Motherboard Standoff Screws

Are Motherboard Standoff Screws Necessary?

Yes, completely. Without standoffs, the motherboard’s exposed solder points rest directly against the metal case tray. Power on the system and you’re creating unintended ground connections across multiple circuits simultaneously. The board typically won’t boot, and depending on what shorts, you can permanently damage the PCB, the power supply, or connected components. Standoffs aren’t optional hardware.

Which Screws Are Used for Motherboard Standoffs?

The mounting screw that passes through the motherboard hole and threads into the standoff is a 6-32 UNC coarse-thread Phillips pan-head screw, typically 3/16 inches in length (about 4.8mm). The standoff body itself also uses 6-32 UNC threading where it screws into the case tray. Both interfaces use the same thread standard in virtually every consumer desktop case sold in North America.

Do All Motherboards Use the Same Standoff Screws?

All standard form factor boards do. The ATX, Micro-ATX, and Mini-ITX specifications define 6-32 UNC as the mounting thread standard. This applies across every current-generation platform, whether you’re building on Intel’s Z890 for a Core Ultra 9 285K or AMD’s X870E for a Ryzen 9 9950X3D build. The exception is proprietary OEM boards from Dell, HP, and some other system integrators, which sometimes use non-standard mounting hole patterns designed to prevent case swaps.

How Tight Should Motherboard Standoff Screws Be?

Finger-tight plus approximately a quarter-turn with a tool. There’s no published torque specification in the ATX standard. The goal is firm, even contact with no PCB flex or visible board warping. If you’re using a screwdriver and it suddenly gets very hard to turn, stop, you’re either bottomed out on a too-long screw or approaching the point where PCB stress begins. Snug and seated is the target, not fully clamped.

What Size Hex Socket Do I Need for Motherboard Standoffs?

A 1/4-inch (6.35mm) hex socket is the correct size for 6-32 UNC standoffs used in the vast majority of consumer PC cases. If your case uses M3 standoffs (more common in European cases and server hardware), you’ll need a 5mm hex socket instead. Most combo standoff tools sold for PC building are sized for the 6-32 standard, so confirm which thread your case uses before buying tools or replacement hardware.

Final Thoughts

The hardware is simple. Six-32 UNC brass standoffs, 6.35mm height, threaded with a 1/4-inch hex socket and secured with Phillips pan-head mounting screws. They come in the case box. A $10 replacement kit covers multiple builds. The installs that go wrong almost always trace back to one of five mistakes: a misplaced standoff, the wrong thread size, a forgotten I/O shield, a stripped screw from over-tightening, or a missing standoff under a sagging board. Get the position audit right before the board goes down, and this part of your build takes under five minutes. That’s time well spent when the alternative is debugging a no-POST system with the board already installed.