4090 and 13900k with SF750 PSU

[no_1_dave]

I currently have the SF750 and after doing a lot of research it seems the Asus Loki and the newer Corsair 850 and 1000 watt PSUs all have some large downsides making the SF750 still the king of SFX power supplies as long as you don't need more power... Now with that in mind I'm planning on keeping my SF750 to use with the new 4090 I just ordered along with Corsair's 2x 8pin to 12pin cable so I don't need to use Nvidia's adapter.

I'm mainly posting this here as I've already made my mind up about doing this, but I do still have that small bit of doubt telling me it maybe a bad idea. Are there any hard numbers out there proving that both the 4090 and CPU will be maxed when gaming? And showing them pushing over 750w between them (without overclocking)? From my own experience I've never seen my 13900k pull over 200w in any game I've played

From what I've read, when gaming the 4090 pulls approx 350w, so that's only 20w more than my current 3080 however the odd game does pull more at times so can anybody tell me which games to test this with..? I'm pretty confident in the reviews which show the SF750 can actually handle more with no trouble at all so the odd game shouldn't cause any issues (hopefully).

 

[no_1_dave]

Hmm what downsides? Aside from Coilwhine which i've experienced with 3 units, i didn't know there was other downsides? I have the Loki 850w version right now and has been great aside from the initial annoyances.

The Loki's apparently have bad coil whine and the newer Corsair are apparently loud and come with crappy cables but also new connectors so changing the cables is a faff.
This is all from what I've read though (multiple sources) and not from my own testing so maybe not as bad as they seem. If my PSU struggles too much I'll probably go for either the 850w or 1000w Loki

TPU had the same result in their review, the average was 118 over 12 games.

Depends how hard you're pushing it (e.g. resolution, RTX, upscaling, frame limiting) and the power limits on the card, but 350 isn't an unreasonable number. 500 is what I'd consider the top-end range for the card.

Adding the numbers up doesn't really tell you much though, since a lot of PSUs (especially lower-end ones) would have problems way before the typical consumption of the system reaches their rated max sustained power. Doing some limiting of the CPU/GPU yourself is the safest thing I can suggest and it should lose you very little performance.

Most of my gaming is 1440p and I limit the frame rate to 144. I don't see the point in going over that when my monitor is 144Hz.
Sometimes I will game on the TV which is 4K 120Hz, but that's only for the odd controller oriented game

My CPU maxes out at 280w and that's when re-encoding 2 4K movies at the same time with ffmpeg pegging the CPU at 100% (I've done a -0.1v offset to achieve this).
If games use 150w and the GPU pulls 450w there should still be headroom as the SF750 is known to be decent spec... We shall see

 

[no_1_dave]

I can tell you from experience having tried 3 separate units of the Loki 850w (Seasonic OEM's from what i've learnt) that they all coil whine but having broken one in over a period of a few months now its improved dramatically to the point where its basically silent. I actually found the cables on the Loki to be really nice, they're not rigid like the corsair units and are very flexible, its like a fabric but with a rubbery coating and they're individually sleeved. It's perfect for ITX builds which im guessing why they took this route with them.

Yea, I've heard good things. Just the coil whine has me on edge cos I can't stand it when it happens. I'll take the Loki route if mine doesn't cut it

 

[no_1_dave]

So far so good
I've put it though a few hours of testing and the highest complete system power I have managed to achieve is 620w.

Not a single game or benchmark has pushed the CPU over 200w while also stressing the 4090 to 400w
I think the only way I am going to be able to push the CPU up to 280w whilst playing a game is to have something else (like encode a video) in the background.

Fit's nicely in my 011 Dynamic Mini as well, the power cable isn't even touching the glass which surprised me