How to choose a power supply for your computer / PC

Joining me today is my good friend, engineer and tech analyst, George Ou, to discuss how to choose the right power supply for your computer / PC needs.

Learn more about independent power supply efficiency testing here:

Video editing software used to create this video:
Cyberlink PowerDirector 15 Ultimate:

Screen captures by Camtasia Studio 9:


See more of Carey’s video’s here:


MiniCactuar says:

Good to see a realistic discussion on power supplies in a world of ever-increasing PSU wattage. Thank you gentlemen.

When I picked my EVGA 550w power supplied I knew I needed 550w by calculating the load that each component will add to the system, plus the extra headroom I desired. Then it was a matter of using the PSU that would most often be in the efficiency sweet spot when doing work on my graphics workstation.

There has to be a rational process when picking each component for a PC build, you can’t just throw parts at it randomly by relying on the latest fads and marketing.

mdd1963 says:

Sorry, but, I also see a trend at hardware forums to think that, given an actual 400 watt constant load, to think a 500 watt PSU is ‘good enough’ as long as it’s some “Gold” or “Platinum” model… Running a PSU at 80% of it’s rated max is asking for trouble, IMO… I’d much rather have 200-300 watts to spare than run a 600 watt PSU at 500 watt load, etc…. I’d recommend having a PSU sized the way electrical engineers size circuit breakers; nominal load X 2. A 300 watt actual load (say a GTX1080Ti with a 7700K) would get at least a 600 watt PSU. Not some starter 430 watt suitable for a business PC with no GPU. (If someone thinks they might seriously contemplate a 2nd GPU for SLI 6 months later, then add another 150-180 watts, about 750 would be nice.)

Malcolm Crabbe says:

I was under the impression that the power rating was how much it could provide, not how much power it drew from the mains. If your PC is at idle then it’s not going to draw 1500w.

Jacqueline Waters-Manesis says:

If you care about aesthetics there are not many offerings for a modular with no ketchup and mustard cables under 650w ( a huge pet peeve of mine in a world full of side windows, who the heck wants to see that ugliness?). There are also other things to consider such as does your graphics card have 2×8 pin PCI inputs, again something you don’t normally find on a PSU under about 650w. Then there are thermal considerations, for example I run a RM750x from Corsair, I don’t think my fan has EVER turned on, meaning it is completely silent and never adds heat dissipation into my case. It is not as black and white as my system consumes X amount of watts so I need a PSU with X amount of watts. My other system which runs 24/7 has an EVGA 650W P2 because it is the smallest power supply that had all the features and a platinum rating…which in energy savings it might not be a huge deal but the 10 year warranty IS. It would be nice if some PSU manufacturers offered the features and benefits these higher end PSU’s offer in lower wattages for those that want/need the features but not the watts. I am sure that many people would consider 200 bucks for a 650w PSU is nutts but I beg to differ. There is a reason why it costs so much beyond the watts and build quality is expressed in a 10 year warranty. What is the value of peace of mind knowing that if something goes wrong with your system it is probably NOT PSU related? You won’t get that in a 50 dollar PSU.

dskwared2u says:

Just finished my first build ever. Doing research online, I found that most experts agreed. I wouldn’t ever need a power supply over 550W. Keep in mind, I’m an accountant not an engineer. The 550’s were actually more readily available than the 450’s on Amazon. I decided on an EVGA Supernova G3 550W. I know you’ll be disappointed Carey, but everything worked properly when I fired her up the first time. Of everything I purchased for the build, I was still worried about being under powered. Now I’m not worried. Thanks for the video. You don’t know till you know!

TSM says:

Excellent advice. Thanks.

dragonfistbs says:

try putting to test system with SLI 2xGTX1080Ti+overclock, this is where the high watts come at use

Richard Dale says:

No 4 way SLI now.

tubawest says:

a 7900x overclocked to the extreme can demand over 300 watts and a single vega gpu overclocked can hit closer to 400 watts power consumption. High power consumption is still possible

cadcock15 says:

Very insightful. Thanks for the video

Jheyo venero roncal says:

real nice information –

Rikki Boodram says:

I am using a 750w PSU with a LGA 2011-v3. High end setup here. Eventually will add 2 GPUs (Using 1 GPU for now) Always good to buy more than you need to give room to grow.

Aj says:

Carey, a great direction in content ! Having someone like “George Ou” on the show shows a real step up or adding to your other good content. Very nice sharing and examples of real case usage. ………………AJ I’d really be interested in his “Blender” work as a thought.

thesmashtvnetwork says:

i got a 1200 wat when my old 500 wat die but it was only thing in stock local and i yet too see power bill go up

FubarMike says:

I might be a little guilty of going overkill on my PSU I have a 650W in my ryzen build with 2 HDDs 1 SSD 1 optical drive and a gtx 950. I have a 650W seasonic. I think I am just paranoid from when my old computer with 3HDDs, a core2duo and a 8600GTS managed to pop a 400W Ultra PSU taking my graphics card and 1 HDD with it

Márk Bikali says:

– 1 gpu 450 (500 max)
– 2-3 gpu 600 (750 max)
– check review and manufacturer here: (FSP is ok, Seasonic is fine, SuperFlower is really good most of the times)

Diego Pablos says:

Guys, you are talking about using a 200 watts PSU for a system using a 1060 with a kabe lake quad core. But if you read the requirements for the 1060, it requires a 400 watts PSU!

T Fantini says:

For a 1500w power supply That is like 15 x 100w light bulbs on a 15 socket lamp, plugged into a socket. Very, very bright room. That always concerned me. So, I use a 600w, which is lots, that is 6 x 100w light bulbs. Still concerning. Think about it. Someone correct me.

Erik Walfridsson says:

His numbers seem low. I doubt his power meter is correct
i5-6600k @ 4,3 GHz, 2x 7200rpm HDD, 1x 2,5″ SATA SSD, 1x GTX 1060 6 GB, 1x GTX 750 Ti, 1 GB running Folding@Home = 238-245 watts (267 watts at the wall with 92% efficiency)
With some work units it may reach 315 watts momentarily (339 watts at the wall with 93% efficiency)
using a Corsair RM1000i in order to always remain within the zero rpm area. (0-400 watt)
At idle this system uses around 48 watts. At THAT low load the efficiency is as low as 79% = 61 watts from the wall.
This is with with a 230 V power grid. The effieciency in the US where the PSU has to work in 120 V mode should be worse.
by the way. “real” AC power can not be caclulated by multiplying current and voltage. The result Carey gets is “apparent power” measured in volt-ampere. (It’s a mess. Check out wikipedia for an explanation)

ddmeltzer8 says:

U can NOT run gtx 1060 in SLI!

Thomas Games says:

I love your vids Carey you helped me fix my pc that was not posting months ago and continue to amaze me today!!!

99beta says:

I purchased an all in one itx case and power supply combo. The power supply was made cheaply and not enough solder was applied to the circuit board. Replaced it with a higher quality brand.

Tom Tom says:

Bought a Corsair HX 850i – yep I went over spec for a single GPU system !

Luke Vincent says:

Thanks, you guys saved me a bundle!!

JimmysTheBestCop says:

Good video. I would like to see you guys hit on overclocking. The 7700k can hit 5ghz and all of the GTX 10xx cards can be OCed past the manufacturer boost mode. All that OCing sucks up more power. EVGA does have a cheap 400watt PSU but if your Ocing your probably coming awfully close to the power limit.

Dont forget about the new category 80+ White which is under bronze.

IanScottJohnston says:

Total load is dynamic, especially in respect to peaks. What you won’t see with your watt meter is those fast transient peaks… all PSU’s will have static & peak load specifications. Your average load could be 80% of the PSU rating but your PC could still crash due to the PSU being underatedi.e. the GTX1060 can routinely experience peak loads of 20W above the average static load (from what I’ve read)…..then there’s the rest of the PC components bouncing around….as it were! One other thing…….a low wattage high quality PSU may actually handle higher peak loads than a cheap but higher wattage PSU. So, you could end up fixing a crashing problem by fitting a higher quality but lower wattage PSU! Whoop whoop!

TheLittleDetails CR says:

Can’t sli 1060’s. Good video

Love Kush says:

In Indian most PCs use 450 watts with 24 Amps is $ 8

Carter Baker says:

Only other place I saw a 1500W PS was with a GIS Server that had 2xGRID Nvidia GPUS.

TheBennedy85 says:

Anyone else try to click the cross on the calculator pop up? lol

Bullettube says:

You have to remember that a power supply rated at 1500 watts is not always drawing 1500 watts when it is on. I bought a Sea Sonic 850 platinum for the price of a 600watt gold unit. It has variable control built in so it only draws what is actually needed, plus the fan only comes on when the unit reaches a certain temp. The heaviest draw I’ve ever seen is just over 550 watts, so the unit is doing its job, and if I add any thing else I know the unit will handle it. Yes, it came with fancy bags that I don’t have any use for! BTW, I have 3 20amp circuits in my home. One is for the garage, one for my shop and one for the kitchen.

Master K says:

Gtx 1070 i7 7700k. Evga 500W (I think it’s “White”). Whenever I play Skyrim I trip my damn breaker after a hour or two, but for internet browsing it NEVER trips. But when I run a extension cord to my living room outlet, doesn’t trip even once even with all day sessions. I figured this way if I upgrade I’d be good & I figured this serious hardware needed 500w. Advice? The extension cord is becoming a pain in the ass lol

gmc9753 says:

I built my own PC (i5 6600, GTX 660 video, 1 hard drive and 2 SSDs) and have it and a 4K monitor plugged into a UPS which will display the power usage. The average usage is around 72 watts. It rarely gets above 100 watts.

DEkTeN says:

The reason why many people like Seasonic is not because of their superiority in efficiency. It is because of the engineering and design of their electric circuitry. Most engineers like seasonic, and other people follow. Just so that you are aware Carey

Earl Stone says:

Thanks Carey & George ,Very informative .See you in the next LIVE

Abdulwahab Abushaigah says:

Thanks Carey and George, that is really helpful. I was always choosing 550W or 500W minimum to be safe, but my PC is i5 2GB low-profile GPU with 550W power supply. I think 550W is overkill, and I should at least replace it with 400W and keep the 550W as a spare part or for future PC.

Gripen90 says:

I have a Thermaltake Toughpower 1500watt PSU I bought back in 2009 and I’m stilll using it.
It has pulled 3x GTX 280/3x GTX 470/3x GTX 580/3x GTX 670/3x GTX780/3x GTX 970/3x GTX 980Ti through the years, and I some cases I have seen max load around 1150~1230watt use at the wall – especially hungry were the 580’s.
Now it’s pulling 2x GTX 1080Ti since 3 way SLi is a thing of the past with pascal.
It’s the best hardware investment I’ve made through the years, and I foresee it will serve me well the next couple of years also.

Bullettube says:

It’s all relative.
I have a 1250 watt micro wave and an electric stove that uses 3000 watts to make bacon and eggs. The oven? I don’t want to even discuss how much that uses! My ac is old and uses more watts in one day then my PC does in a month! The electric fan on my gas furnace and my vacum cleaner are big electric hogs as well.

Erik Walfridsson says:

The effieciency of a PSU is highest around 50% load, so you machine cosnumes 300 watts you should choose one rated 600 + a margin to make room for future upgrades. This calculation works ASSUMING that the computer is used for gaming most of it´s uptime. If is on idle most of the time it will be more economical to have a weaker PSU just like they say. BUT one must also keep in mind that the PSU will wear out faster at high load. Is it worth it to buy a cheaper PSU, run it at 100% load and blow an electrolytic capacitor in a few years, possibly destroying the rest of your hardware?

ddmeltzer8 says:

PSU`s run most efficiently when running at 60-80%!Thats where they give the most even output.

Jayson Cordrey says:

Carey and friend are correct about the power supply. I did my own experiment and my system draws less than 100w when doing daily stuff on the pc. I am now going to down grade my power supply from a 550 to a 450 power supply.

Amiga Wolf says:

A 1500w PSU do NOT use 1500w when you use PC parts that uses a total wattage of only 400w max in games (an example), but yes if you have a Game PC that uses about 400w max in games (an example), it’s best to buy a 550 a 600w PSU, so if you buy a CPU or GPU later after a upgrade that uses more wattage, you don’t have to buy a new PSU.

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