Best 850W Power Supplies Under £100

1. MSI MPG A850GS PCIE5 Power Supply Unit, 850W, 80 PLUS Gold, ATX 3.1, PCIe 5.1 50 series GPU Support,Native 12V-2x6, Cables with Dual-color 12V-2x6 connectors, ATX PSU, Embossed Jacket Cables

£84.99 | ★★★★☆ (4.0)

This is the one to buy if you want the best 850W power supplies under £100 without any compromise on modern spec. The MPG A850GS is MSI's latest ATX 3.1 and PCIe 5.1 compliant unit, which means it's fully ready for Nvidia's 50-series GPUs right out of the box. The native 12V-2x6 connector handles the high transient loads these cards produce without any adapter faffing about.

What sets it apart from the older MPG A850G (which is also in this roundup) is the updated ATX 3.1 spec and those dual-colour embossed jacket cables. They look genuinely smart inside a windowed case. Not everyone cares about aesthetics in a PSU, but when you're paying under £75 and getting this level of presentation, it's a nice bonus rather than a gimmick.

Efficiency sits at 80 Plus Gold, so you're looking at up to 92% efficiency at typical loads. The fan runs in semi-passive mode at low loads, which means near-silent operation during light gaming or desktop use. Under full load it spins up, but it's not loud. MSI uses Japanese 105°C capacitors throughout, which is exactly what you want to see at this price point.

The fully modular design keeps cable clutter manageable. You get enough connectors for a dual-GPU setup (not that most people need that), and the flat cables route cleanly behind the motherboard tray. For anyone building around a current-gen GPU, this is the obvious first choice among the best 850W power supplies under £100.

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2. MSI MPG A850G PCIE5 Power Supply Unit, UK Plug - 850W, 80 Plus Gold Certified, Fully Modular ATX 3.0, PCIe 5.0 GPU Support, Japanese 105°C Capacitors, 0% RPM Mode, Flat Cables - 10 Year Warranty

£89.99 | ★★★★½ (4.7)

The original MPG A850G has been around long enough to build a proper reputation, and it's earned it. This is the unit that proved MSI could compete seriously at the 850W Gold tier, and the 10-year warranty is the clearest signal of confidence you'll find anywhere in this price bracket.

It runs ATX 3.0 rather than the newer 3.1, and uses the 12VHPWR connector rather than the updated 12V-2x6. For most users that's a non-issue, but if you're buying specifically for a 50-series GPU, the GS variant above is the smarter choice. For everything up to and including RTX 4090 class hardware, the A850G handles it without breaking a sweat.

The 0% RPM mode is genuinely useful. Below about 30% load the fan stops entirely, making this one of the quietest PSUs you'll find among the best 850W power supplies under £100. It only spins up when you're actually pushing the system hard. Japanese 105°C capacitors are present throughout, and the flat cables make routing straightforward even in tighter cases.

Owner feedback on Amazon UK is consistently positive, with reliability and quiet operation being the most commonly praised aspects. At around £90, it's not the cheapest here, but the decade-long warranty makes the price easy to justify.

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3. MSI MAG A850GL PCIE5 Power Supply Unit, 850W, 80 Plus Gold, Fully Modular, ATX 3.0, PCIe 5.0 GPU Support, Black Flat Cables, 7 Year Warranty

£89.99 | ★★★★☆ (4.4)

The MAG A850GL sits in MSI's more accessible MAG line rather than the premium MPG range, but don't let that put you off. For a first build or someone who just wants a reliable, no-drama PSU, this is a proper decent option. The 7-year warranty is shorter than the MPG A850G's decade-long cover, but it's still well above average for the price.

Setup is straightforward. The fully modular design means you only plug in what you need, which reduces the intimidation factor for first-time builders considerably. The black flat cables are tidy and easy to route, and the PCIe 5.0 support means you won't need to replace this unit when you upgrade your GPU for the next few years.

It runs ATX 3.0, so it's not the very latest spec, but for anyone not specifically targeting a 50-series GPU right now, that's not a meaningful limitation. Gold efficiency keeps running costs reasonable, and the unit is quiet under typical gaming loads. At £88, it sits in a comfortable middle ground among the best 850W power supplies under £100.

If you're building your first PC and want something from a recognisable brand with solid warranty cover and an easy installation experience, the MAG A850GL is the one to go for.

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4. Cooler Master MWE 850 Gold V2 Fully Modular PSU (UK Plug) - 80 PLUS Gold 850W Power Supply Unit, Flat Black Cabling, 120mm HDB Fan, High-Temperature Threshold

★★★★½ (4.5)

Here's the thing about the Cooler Master MWE 850 Gold V2: it's been around long enough that we actually know how it performs in the real world. That matters. Newer units from lesser-known brands can claim all sorts on the spec sheet, but the MWE V2 has thousands of owner reviews and a proven track record across multiple years of use.

The HDB (Hydrodynamic Bearing) fan is genuinely quiet. It's not a semi-passive design, so it runs continuously, but at low to moderate loads you'd struggle to hear it over your case fans. The high-temperature threshold means it ramps up sensibly under load rather than spinning at full speed unnecessarily.

Flat black cables keep things tidy, and the fully modular design is exactly what you want at this price. It's ATX 2.x spec rather than ATX 3.0 or 3.1, which is the honest limitation here. For current-gen GPUs up to RTX 4080 class, that's fine. For 50-series cards, you'd want one of the ATX 3.0 or 3.1 units higher up this list. But for an existing build, a budget upgrade, or a secondary rig, the MWE V2 is a proper bargain.

Among the best 850W power supplies under £100, this is the one with the most proven reliability data behind it. That counts for a lot.

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5. Fractal Design Ion 3 Gold 1000W Black 80 PLUS Gold Certified Fully Modular ATX12V 3.1 Power Supply Unit PSU

£89.99 | ★★★★★ (5.0)

Technically this is a 1000W unit rather than 850W, but at just under £100 it's impossible to ignore. Fractal Design has a strong reputation for quality components, and the Ion 3 Gold represents their latest ATX12V 3.1 compliant offering. If you're thinking about upgrading your GPU in the next year or two, the extra headroom is genuinely useful.

ATX12V 3.1 compliance means it handles transient spikes properly, and the fully modular design keeps cable management clean. Fractal's cable quality is consistently good, with flexible, well-sleeved options that route easily in most cases. The Gold efficiency rating keeps it competitive on running costs.

The main caveat is that it's a newer product with limited owner feedback so far. Fractal's track record is strong enough that this isn't a major concern, but it's worth noting if you prefer buying units with years of real-world data behind them. Among the best 850W power supplies under £100 (or just over), this is the pick for anyone who wants to buy once and not think about their PSU for a decade.

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6. MONTECH Century II - 1200W High-End ATX Gaming Power Supply - 80 Plus Gold & Cybenetics Platinum - Fully Modular - ATX 3.1 & PCIe 5.1 Ready with 12V-2x6 Cable - 10 Years Warranty

★★★★½ (4.7)

1200W for £80. That's the headline, and it's a genuinely remarkable figure. The MONTECH Century II is the most powerful unit in this entire roundup, and it costs less than several 850W options. The dual certification (80 Plus Gold and Cybenetics Platinum) adds credibility to what might otherwise look too good to be true.

ATX 3.1 and PCIe 5.1 compliance with a native 12V-2x6 cable means it's ready for 50-series GPUs. The 10-year warranty is as long as you'll find anywhere. MONTECH is a Taiwanese brand that's been building a solid reputation in the PSU market over the past few years, and the Century II has received positive coverage from hardware review sites.

So what's the catch? Mainly that MONTECH doesn't have the same brand recognition as MSI, Cooler Master, or Fractal Design in the UK. Owner feedback is more limited than the established brands. And 1200W is more than most builds will ever need, which means you're paying for capacity you won't use. But if you're building a high-end rig and want maximum headroom, this is extraordinary value among the best 850W power supplies under £100 (and well beyond).

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7. Tacens Anima APIII850, ATX 850W Power Supply, SMD and DC-DC Technologies, 85% 12V Efficiency, Ultra-Quiet 12cm Fan, 105º Japanese Capacitors, Carbon Fiber Cables, Black

£34.58 | ★★★★☆ (4.4)

Under £41 for an 850W PSU with Japanese capacitors and DC-DC technology. That's either a bargain or a red flag, depending on how you look at it. Tacens is a Spanish brand with a reasonable presence in European markets, but they're not well-known in the UK and the owner feedback pool is thin.

The spec sheet is actually decent. SMD and DC-DC technologies are legitimate quality indicators, the 85% 12V efficiency claim is plausible for a Gold-adjacent unit, and 105°C Japanese capacitors are exactly what you want to see. The carbon fibre cables are a nice aesthetic touch. But here's the honest assessment: at this price, something has to give. Whether that's the quality of secondary components, the accuracy of the efficiency claims, or the longevity of the unit under sustained load, it's hard to know without independent testing data.

Use this for a secondary build, a budget office PC, or a stopgap while you save for something better. Don't put it in a high-end gaming rig running an RTX 4080 at full tilt. As the only credible option under £50 in this roundup of the best 850W power supplies under £100, it earns its place, but go in with realistic expectations.

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8. Tecnoware Power Supply Typhoon 850W, 80 PLUS Gold, Full Modular, Gaming, Silent 12cm Fan, Japanese 105°C Capacitors, DC-DC Circuit, Flat Cables

★★★★☆ (4.4)

£27 for a fully modular 850W Gold PSU. That number should give you pause. Tecnoware is an Italian brand that's been around for a while in European markets, but at this price point the claims on the spec sheet (80 Plus Gold, Japanese 105°C caps, DC-DC circuit) are very difficult to verify independently.

There's almost no owner feedback on Amazon UK for this unit. That's not necessarily because it's bad, it could simply be a new listing, but it means there's no real-world data to draw on. The flat cables and fully modular design are genuine positives, and if the Gold certification is legitimate it would represent extraordinary value.

But. And this is a significant but. Your PSU is the one component that can take out your entire system if it fails badly. Saving £50 on a PSU is not worth the risk if the unit isn't up to the job. Treat the Tecnoware Typhoon as a last resort or a very temporary solution, not a serious contender among the best 850W power supplies under £100. If budget is genuinely tight, the Tacens above at least has some brand presence and slightly more data behind it.

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