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How to Choose a Power Supply (and How Many Watts You Actually Need)
The power supply (PSU) is the least exciting part in the box and the one that matters most to get right. It feeds every other component — and it's the only part that can take the whole PC down with it if it's a bad one. Here's how to size it, how to read the ratings, and where the floor is.
Start here: wattage by graphics card
The graphics card is by far the hungriest part in a gaming PC, so wattage is chosen by GPU first, everything else second. Find your card (or the one you're planning to upgrade to):
| Graphics card | Card's power draw | PSU we'd buy |
|---|---|---|
| Intel Arc A750 (our Budget Build) | ~225W | 550W |
| Radeon RX 7600 | ~165W | 550W |
| GeForce RTX 5060 | ~180W | 550W |
| Radeon RX 9060 XT 16GB (our Mid-Range Build) | ~160W | 650W |
| GeForce RTX 5060 Ti | ~180W | 650W |
| GeForce RTX 4070 | ~200W | 650W |
| Radeon RX 7700 XT | ~245W | 700W |
| GeForce RTX 5070 | ~250W | 750W |
| Radeon RX 7800 XT | ~263W | 750W |
| GeForce RTX 4070 Super | ~220W | 750W |
| Radeon RX 9070 XT (our High-End Build) | ~304W | 850W |
| GeForce RTX 5070 Ti | ~300W | 850W |
| GeForce RTX 5080 | ~360W | 850W |
Card draws are typical board-power figures; recommendations follow the card makers' own guidance and already include headroom for the processor and the rest of the system. Planning a GPU upgrade later? Size the PSU for the card you're upgrading to, and you'll only buy a power supply once.
The headroom rule of thumb
If you'd rather do the math than use the table: add up your system's realistic peak draw, then buy a PSU rated roughly 40–50% higher. Here's what that looks like in our own builds:
- Budget Build: ~340W peak system draw → 550W PSU.
- Mid-Range Build: ~250W under gaming load → 650W PSU (generous — it leaves room for a future GPU step-up).
- High-End Build: ~600W worst case → 850W PSU.
Why the cushion? A PSU runs most efficiently and quietly in the middle of its range, graphics cards pull brief power spikes above their rated draw, and headroom today is an upgrade you don't have to make tomorrow. Too much wattage isn't harmful — just wasted money past a point. Too little means shutdowns mid-game, or worse.
80 Plus ratings, in plain English
"80 Plus" measures efficiency: how much of the power pulled from the wall actually reaches your parts, versus how much is wasted as heat. The ladder runs Bronze → Silver → Gold → Platinum → Titanium, each step a few percent more efficient. A Gold unit turns roughly 90% of wall power into PC power; a Bronze unit, a few points less.
The thing nobody tells beginners
80 Plus is an efficiency rating, not a quality rating. It says nothing about whether the unit is well-built or will protect your parts. A no-name "Gold" unit can be junk; a good Bronze unit from a reputable brand (like the one in our Budget Build) is a perfectly safe buy. Judge quality by brand reputation and warranty length — the PSUs in our builds carry 5- and 10-year warranties, and that warranty is the manufacturer putting a number on how long they expect it to live.
Practical advice: Bronze from a good brand for a budget build, Gold for anything mid-range and up (it also runs cooler and quieter). Beyond Gold, you're paying for electricity savings that take years to add up.
Modular, semi-modular, non-modular
- Non-modular: every cable is permanently attached. Cheapest. You tuck the spares somewhere in the case and forget them.
- Semi-modular: the essential cables are attached; the rest plug in only if you need them. The middle path.
- Fully modular: every cable detaches. Easiest to build with, cleanest result, small price premium. Both our mid-range and high-end picks are fully modular.
One safety rule that comes with modular units: never reuse cables from a different modular PSU. The plugs look identical, but the wiring at the PSU end isn't standardized between brands — mixing cables can fry components. Use the cables that came in the box with your unit, full stop.
Connectors: the one thing to check before checkout
- Graphics cards plug in with 8-pin "PCIe" power cables (sometimes two of them — the Arc A750 in our Budget Build needs both, and its PSU includes them). Count what your card needs and confirm the PSU has it.
- Newer high-end NVIDIA cards use a single compact connector (called 12V-2x6, formerly 12VHPWR). A modern "ATX 3.x" PSU includes it natively — both our 650W and 850W picks do, which is one reason they're on the list.
- Everything else — motherboard, drives — uses standard cables that every PSU includes.
Why you don't cheap out on this part
Every component you own eats through this one box. A failing bargain-bin PSU doesn't just die quietly — it can deliver dirty power for months (random crashes, killed drives) or take other parts with it on the way out. It's also the part most likely to be reused in your next build: a good one with a 10-year warranty can serve three PCs. The correct budget move is never the cheapest unit on the shelf — it's a reputable brand, sensible wattage, and a real warranty. The three below are exactly what we spec, at three sizes:
| Power supply | Rating | Used in | Price | |
|---|---|---|---|---|
| MSI MAG A550BN 550W | 80+ Bronze, 5-yr warranty | Budget Build | $54.99 | View on Amazon |
| MSI MAG A650GL 650W | 80+ Gold, fully modular, 10-yr warranty | Mid-Range Build | $90.77 | View on Amazon |
| MSI MAG A850GL PCIE5 850W | 80+ Gold, fully modular, ATX 3.0, 10-yr warranty | High-End Build | $109.99 | View on Amazon |
Quick recap
- Size by graphics card first — use the table.
- Add ~40–50% headroom over your system's peak draw.
- 80 Plus = efficiency, not quality. Brand + warranty = quality.
- Fully modular is a convenience worth a small premium; never mix modular cables between units.
- Check the GPU connectors before you buy, especially on newer NVIDIA cards.