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).

 

[rare]

I would power limit the 4090 to about 70–80% as a good start. Cyberpunk seems a good one to load up especially with heavy RT enabled.

I think the 750 can handle about 850 max but you are asking quite a lot of it with that combo, though I’m sure it can be made to work well. I ran a 6950XT and a 12700k on the same Psu before.

 

[Jay85]

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).

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.

I think for a 4090 and a 13900k i would aim for 850w minimum, the 750w feels like its cutting it really close.

 

[Jay85]

For reference though i ran a 12700k and a 3090 on a SF600w for a few months and it worked just fine but again during load, you could tell the psu was really pushing hard as the fan would spin pretty fast which makes a lot of unwanted noise.

 

[Tetras]

From my own experience I've never seen my 13900k pull over 200w in any game I've played

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

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).

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.

 

[bakes0310]

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.

I think for a 4090 and a 13900k i would aim for 850w minimum, the 750w feels like its cutting it really close.

You going to upgrade the to the 1000w Loki.

 

[Jay85]

You going to upgrade the to the 1000w Loki.

Probably not, not gonna do anything until i see the specs for the 5090/5080 and decide then. By that time there should be some good variation of ATX3.0 psu's and hopefully a few more in the SFX/L range.

 

[bakes0310]

Probably not, not gonna do anything until i see the specs for the 5090/5080 and decide then. By that time there should be some good variation of ATX3.0 psu's and hopefully a few more in the SFX/L range.

Has the coil whine in your previous returns put you off them, is you current one been okay generally speaking. Shame your having issues as there's been some glowing reviews, which I assume you saw and help with your purchase decision on it.

 

[Jay85]

Has the coil whine in your previous returns put you off them, is you current one been okay generally speaking. Shame your having issues as there's been some glowing reviews, which I assume you saw and help with your purchase decision on it.

It did for awhile but i gave it another chance and decided to wear one in by just using it and its gotten a lot better to the point where i don't notice it at all now. It's pretty much back to how my SF750w was and its whisper quiet.

Would i get another? I don't know, i know they're Seasonic OEM's... a majority of these SFX-L's are hence all sharing the same problems. I will do my research if i upgrade again and see which ones are OEM's from which manufacturer and decide from there on like i did with this one.

Reliability wise, i haven't had any issues with this one, its been solid and a great performer. The fan is silent too which is one of the reasons why i jumped up to a SFX-L in the first place.

 

[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

 

[Jay85]

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



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

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.

 

[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

 

[Jay85]

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

Its annoying but try and run it in, you might get lucky and get one with no whine. I was an early adopter when they first launched so things might have improved since then.

I haven't tested one since tbh so can't tell you what the new batch are like. Was fun returning £200 psu's twice though lol and having to explain to the vendor what the issue was lol.

 

[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

 

[Jay85]

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

Sounds good mate, i think you'll be fine for awhile until the next gpu releases. Hope efficiency will be good on next gen for both sides or 3 sides if Intel joins in.