PSU Calculator – Find the Right Power Supply for Your PC

Pick your parts and see the wattage. Results include 20% buffer so you don’t run your PSU at the limit.

What Wattage Do You Need

I run a Ryzen 5 with RTX 4070 and my whole system pulls around 380W gaming. Got a 650W PSU and never had issues. If you have similar specs, 650W works.

RTX 4080 or 4090 is different, those cards are hungry. 850W minimum there. And RTX 5090 is just crazy, 575W for the GPU alone, you need 1000W like NVIDIA says.

Office PC or HTPC? 450W is plenty. You’re not pushing anything hard anyway.

Workstation with Threadripper or dual GPUs? 1200W+. But if you’re building that you probably already know what you’re doing.

GPU Power – The Numbers

RTX 5090 is a space heater at 575W. The 5080 is more sane at 360W. 5070 Ti and 5070 are 300W and 250W, pretty normal for high end cards.

RTX 4090 says 450W on the box but I’ve seen it spike to 600W in Cyberpunk. The 4080 cards sit around 320W. 4070 Ti Super is 285W, regular 4070 about 200W. The 4060 Ti and 4060 are actually efficient, 165W and 115W.

AMD is similar. 7900 XTX around 355W, 7900 XT about 315W. The 7800 XT that everyone recommends is 263W. 7700 XT is 245W and 7600 only 165W which is nice for smaller builds.

If you have RTX 30 series it still works great. 3090 is about 350W, 3080 around 320W, 3070 is 220W, 3060 around 170W.

RX 6000 cards are similar, 6900 XT and 6800 XT both around 300W.

Intel Arc is worth mentioning, A770 is about 225W and A750 around 190W. Drivers are finally decent.

CPU Power

Intel K chips are power hogs. i9-14900K pulls 253W under load. The 125W TDP on the box is only for base clock – real world usage goes way higher. i7-14700K draws about the same. i5-14600K hits 181W.

Non-K chips like i5-14400 stay at 65W which is way more reasonable.

AMD is way better on power. My friend has a 9950X and it maxes around 170W which is nothing compared to Intel flagships. The 9800X3D everyone wants is only 120W. Ryzen 5 9600X and Ryzen 7 9700X barely touch 65W.

Older chips are similar. 7950X was 170W, 7900X around 120W. The 7800X3D and 7700X are about 105W.

If you want lower power bills, go AMD. Intel trades efficiency for raw performance in threaded workloads.

Why Bigger Is (Usually) Better

PSUs run most efficient at 50% load. A 500W system on a 1000W PSU hits that sweet spot perfectly. On a 600W PSU you’re at 83% load – still fine but less headroom for spikes.

Modern GPUs spike hard. RTX 4090 can hit 600W for a few milliseconds even though it’s rated at 450W. Cheap PSUs trip their overcurrent protection and your PC just dies mid-game. No BSOD, no warning. Just off.

I had this happen with a budget Thermaltake. Switched to Corsair RM850x and the problem went away.

RTX 30 series was even worse for this. The 3080 and 3090 were notorious for tripping PSUs that should have been enough on paper.

80 Plus Ratings – What They Mean

80 Plus Bronze = 85% efficiency at typical loads
80 Plus Gold = 90% efficiency
80 Plus Platinum = 92% efficiency
80 Plus Titanium = 94% efficiency

The missing percentage turns into heat. More heat = louder fan = more wear on components.

Bronze is fine for most builds under 600W.

Gold is worth it for higher power systems. The efficiency difference on a 500W system is like $3-4/month on your electric bill depending on rates and usage. Over 5 years that adds up to $200+ though.

Platinum and Titanium? Server stuff mostly. For gaming it’s overkill.

Modular vs Fixed Cables

Fully modular: only plug in cables you need. Cleaner build, better airflow. Costs $20-40 more.

Semi-modular: main 24-pin and CPU cables attached, everything else removable. Best value for most builds.

Non-modular: all cables permanently attached. Cheapest option. You end up stuffing extra SATA and molex cables behind the motherboard tray. Works fine, just uglier.

For building, modular is way easier. No fighting with extra cables during install.

What About Everything Else

RAM: about 3W per stick. DDR4 or DDR5, doesn’t matter much. With 4 sticks you add maybe 12W total.

NVMe SSD: 5W each roughly.
SATA SSD: 3W each
HDD: anywhere from 5 to 8W, faster drives use more
Case fans: 2-3W each. With 6 fans that’s 15W or so.

Motherboards vary. High end X670E or Z790 draws 70-80W. B650/B760 around 60W. Budget A620/H610 more like 50W.

Cooling: stock coolers pull maybe 3W. Tower air coolers 5W. 240mm AIO around 10W. 360mm AIO around 15W. Custom loop with D5 pump hits 25-30W.

All this extra stuff adds up. A “500W system” on paper ends up being 550-600W once you count everything.

Signs You Need a Bigger PSU

Your PC just turns off while gaming. No blue screen, no error, just black and silence. This drove me crazy until I realized it was the PSU giving up during GPU power spikes.

Screen goes black randomly but fans still spin. GPU brownout.

System restarts when you launch demanding games or benchmarks.

Coil whine getting progressively worse over time.

New GPU won’t POST or system won’t boot after upgrade.

PSUs older than 5 years that start acting weird should be replaced. Capacitors wear out, and a dying PSU can take your motherboard with it.

Brands I Use

Corsair RM/RMx series – this is what I run in my main rig.
Seasonic Focus/Prime – they make PSUs for half the industry anyway.
be quiet Pure Power/Straight Power – German, focused on quiet operation.
EVGA SuperNOVA – good value if you can still find them.

What I skip: unknown Amazon/AliExpress brands, “gaming” PSUs with RGB on the unit itself, super cheap models even from known brands.

FAQ

Can my PSU be too big

No. A 1000W PSU on a 400W system just runs at 40% load. Slightly below peak efficiency but nothing bad happens. You just overpaid.

Do I need to upgrade PSU for new GPU

Went from 3060 to 4070 myself, kept my 650W and it runs fine. But 4090 is a different beast, had to get 850W for that.

What about 12VHPWR connector

RTX 40/50 series use this new connector. Either get a PSU with native 12VHPWR output or use the adapter that comes with the card. The melting connector issues were mostly user error – not pushing it in fully. Native is cleaner though.

PSU clicking noise – normal or bad

Click at startup = relay switching, totally normal. Click under heavy load = possibly coil whine, annoying but not dangerous. Constant random clicking = something is wrong, replace it.

How long do PSUs last

Good brands: 10+ years easily. Most quality units have 7-10 year warranty. Cheap units: maybe 3-5 years before caps start bulging.

650W vs 750W for RTX 4070

Either works. 750W gives more headroom if you upgrade CPU later or add more drives. Price difference is usually $10-20. I’d go 750W.

Worth buying used PSU

I wouldn’t. No way to know how many hours it has or condition of capacitors. PSUs are one component I always buy new.

SFX vs ATX size

ATX is standard size, fits most cases. SFX is compact for mini-ITX builds. SFX costs more for same wattage. Check your case manual before ordering.

Does brand of PSU affect GPU boost

Somewhat. Cleaner power delivery = more stable voltage = GPU can maintain boost clocks better. Cheap PSU with voltage ripple might cause minor downclocking. Real world difference is maybe 1-2%.

Single rail vs multi rail

Old debate. Single rail = full amperage available on 12V. Multi rail = split into sections with separate overcurrent protection. Modern quality PSUs handle either fine. Single rail is simpler.