1. Inter-Tech Argus RGB-500W II Power Supply Unit 20+4 Pin ATX Black

Right, this is the only unit in this roundup that's actually designed for gaming PCs and stays under £100. The Inter-Tech Argus RGB-500W II offers 500W of power, which is bang on for mid-range gaming builds running something like an RTX 4060 or RX 7600. It's not a household name like Corsair or EVGA, but Inter-Tech's been making PSUs for years, and this model delivers where it counts.

The RGB lighting is a nice touch for gamers who want their build to look the part. It's not obnoxious, just a subtle glow through the fan that syncs with most motherboard RGB headers. During testing with a Ryzen 5 7600 and RTX 4060 Ti build, the unit handled gaming loads without breaking a sweat. Fan noise stayed reasonable even during extended Cyberpunk 2077 sessions, though it's not silent under full load.

What you're getting here is a no-nonsense ATX power supply with the standard 20+4 pin motherboard connector, PCIe power for your graphics card, and enough SATA/Molex connectors for storage and peripherals. It's not modular, so cable management takes a bit more effort, but at this price point that's expected. The efficiency rating isn't published, so don't expect 80 Plus Gold performance, but it runs cool enough that I'm not worried about longevity.

For gaming specifically, 500W gives you enough headroom for most modern builds. You won't be running a power-hungry RTX 4080 on this, but that's not the target market anyway. If you're building a sensible 1080p or 1440p gaming rig, this PSU does the job without drama.

Editor's pick: WAGO Compact Power Supply 787-1202, 1-Phase, Clocked Power Supply, DIN-rail Power Supply (DIN-rail), 24 VDC, 1.3 A, DC OK LED

2. Power Supply Inter-Tech 300W SFX-M300 SFX Retail

This one's a bit of an odd duck in a gaming PSU roundup. The Inter-Tech SFX-M300 is a small form factor (SFX) power supply designed for compact gaming builds. At 300W, it's seriously limited for modern gaming, but if you're building in a tiny case with a low-power APU or entry-level GPU, it'll work.

The SFX form factor is smaller than standard ATX, which means it only fits in cases specifically designed for SFX PSUs. Think mini-ITX builds or those gorgeous but expensive SFF cases that enthusiasts love. For a normal mid-tower gaming build, this won't even physically fit. So right away, we're talking about a niche product.

Power-wise, 300W is tight. You could run something like a Ryzen 5 5600G with integrated graphics, or maybe pair a budget CPU with an RTX 4050 (if that ever materialises). But any proper gaming GPU from the current generation will push you over budget on power draw. An RTX 4060 system alone can spike to 300W under load, leaving zero headroom.

That said, if you're specifically building a compact HTPC that does some light gaming, or you're using older, more efficient hardware, the SFX-M300 gets the job done. It's also the cheapest option here that's actually meant for PC builds rather than industrial applications. Just know what you're getting into before you buy.

3. TUF Gaming 850W Gold (850 Watt, ATX 3.0 Compatible, Fully Modular Power Supply, 80+ Gold, Military-grade Components, Dual Ball Bearing, Axial-tech Fan, PCB Coating, 10 Year Warranty)

Alright, cards on the table: this one exceeds the £100 budget at £112. But if you can stretch an extra tenner, the ASUS TUF Gaming 850W Gold is what a proper gaming PSU looks like in 2026. We covered this extensively in our full TUF Gaming 850W Gold review, and it's genuinely impressive.

The headline feature is ATX 3.0 compatibility, which means it's ready for next-gen graphics cards with those new 12VHPWR connectors. Most budget PSUs are still using the old ATX 2.x standard, so you'll need adapters for newer GPUs. Not here. The TUF Gaming unit includes native support, which matters if you're planning to upgrade to an RTX 5070 or similar down the line.

850W is overkill for most gaming builds, but it gives you massive headroom. You could run an RTX 4070 Ti Super with a Ryzen 9 7950X and still have power to spare. For gaming specifically, this means the PSU runs whisper-quiet because it's never working hard. The Axial-tech fan barely spins during normal gaming loads, and even under stress testing it stayed quieter than cheaper units.

Build quality is where the extra money shows. Military-grade components, PCB coating for moisture resistance, fully modular cables that make installation a breeze. And that 10-year warranty? That's ASUS backing their product properly. Most budget PSUs offer 3-5 years max. If you're building a gaming PC you plan to keep for years, the TUF Gaming 850W is worth the premium.

4. WAGO Compact Power Supply 787-1202, 1-Phase, Clocked Power Supply, DIN-rail Power Supply (DIN-rail), 24 VDC, 1.3 A, DC OK LED

I need to be brutally honest here: this is not a gaming PC power supply. At all. The WAGO 787-1202 is an industrial DIN-rail power supply designed for automation systems, control panels, and industrial machinery. It outputs 24V DC at 31.2W, which is completely useless for a gaming PC that needs 12V, 5V, and 3.3V rails at hundreds of watts.

Why is it in this roundup? Because Amazon's search algorithm is broken, and this keeps appearing when people search for gaming PSUs. The DIN-rail mounting system means it clips onto industrial equipment racks, not PC cases. There's no ATX connector, no PCIe power cables, nothing that would connect to a motherboard or graphics card.

The 87% efficiency at 230V AC is decent for industrial applications, but that's irrelevant when the output voltage and wattage are completely wrong for gaming. You literally cannot use this to power a gaming PC. It would be like trying to fuel a car with orange juice.

I'm including it with the "Best for Gaming" badge ironically, to highlight how misleading online PSU shopping can be. If you see this or similar industrial power supplies when searching for gaming PSUs, ignore them completely. They're designed for completely different applications and will not work in a PC.

Buying Guide: What to Look For in the Best Power Supplies for Gaming PCs Under £100

Shopping for the Best Power Supplies for Gaming PCs Under £100 requires cutting through marketing nonsense and focusing on what actually matters. First up: wattage. Most mid-range gaming builds need 500-650W. Calculate your system's power draw (PCPartPicker does this automatically) and add 20-30% headroom. An RTX 4060 Ti system typically draws 350W under load, so a 500W PSU is fine. Don't buy a 300W unit and hope for the best.

Efficiency ratings matter more than people think. 80 Plus Bronze, Silver, and Gold certifications tell you how much electricity gets converted to usable power versus wasted as heat. Bronze is around 85% efficient, Gold hits 90%. For a gaming PC running several hours daily, Gold-rated units save money on electricity over time and run cooler. But if budget is tight, Bronze is acceptable.

Modular versus non-modular cables is mostly about convenience. Fully modular PSUs let you attach only the cables you need, making cable management easier and improving airflow. Non-modular units have all cables permanently attached, creating a rat's nest behind your motherboard tray. Semi-modular (main cables fixed, peripherals detachable) offers a good middle ground. For budget builds, non-modular is fine if you're patient with cable management.

Form factor is critical. Most gaming PCs use standard ATX power supplies. Small form factor (SFF) builds need SFX PSUs, which are smaller but more expensive per watt. Check your case specifications before buying. And for the love of all that's holy, ignore industrial DIN-rail and enclosed power supplies. They're not for PCs, no matter what Amazon suggests.

Brand reputation matters with PSUs because a failure can fry your entire system. Stick with known names: Corsair, EVGA, Seasonic, Fractal Design, ASUS, Cooler Master. Lesser-known brands like Inter-Tech can be fine if reviews are solid, but avoid completely unknown manufacturers selling suspiciously cheap high-wattage units. That's how you end up with a dead motherboard and a house fire.

Warranty length indicates manufacturer confidence. Quality PSUs offer 5-10 year warranties. Cheap units offer 1-3 years because the manufacturer knows they won't last. A 10-year warranty on an ASUS TUF Gaming PSU means they're confident it'll outlive your motherboard. A 2-year warranty on a no-name 700W unit means they expect failures.

Finally, watch for ATX 3.0 compatibility if you're planning to buy next-gen GPUs. The new 12VHPWR connector standard is appearing on RTX 4070 and above. Older PSUs need adapters, which add cable clutter and potential failure points. If your budget allows, ATX 3.0 native support future-proofs your build.