Will a 650W 80+ Gold PSU be enough for an RTX 3070 TI FTW3

[WinWX]

Hey all, I just got a new EVGA GeForce RTX 3070 Ti FTW3 ULTRA GAMING (which I haven't installed yet) and according to the EVGA website, it mentions a minimum 750W PSU is required. Using PCPartPicker, I've created my build with the new video card and all the remaining parts, including the Seasonic FOCUS GX-650, 650W 80+ Gold. According to that, the build consumes 515W plus 23W of the water pump that wasn't included (538W total), so why a 750W PSU is required? Should my 650W PSU be enough?

[stage]

Because the PSUs don't run at 100% all the time. They have efficiency ratings depending if they have none, standard, bronze, silver, gold or platinum certification (and even those can't be trusted as many times they perform lower than what they are rated for). Most of them will run between 80 to 85% efficiency. So 80% out 650 is 520. So you have no headroom and you are behind by default from your own calculation.

[Pixelfie]

RTX cards often have spikes that are way above TDP for a few ms. So that could make it go above 650w. 650 might be enough but 750w would be better if possible. Also Seasonic had issues with these power spikes a while ago. I think it's fixed now but if you own the PSU for some time already it may be worth checking if yours is affected by this.

[Mattias Edeslatt]

@WinWX

 

2 hours ago, stage said:

Because the PSUs don't run at 100% all the time. They have efficiency ratings depending if they have none, standard, bronze, silver, gold or platinum certification (and even those can't be trusted as many times they perform lower than what they are rated for). Most of them will run between 80 to 85% efficiency. So 80% out 650 is 520. So you have no headroom and you are behind by default from your own calculation.

That is not how the efficiency of a PSU works. If a PSU is rated for 650 W it delivers 650 W to the system, but with 80 % efficiency it draws 812 W from the wall to deliver the 650 W

 

 

https://www.tomshardware.com/reviews/psu-buying-guide,2916-3.html

Quote

Example:

Let’s assume we’re really pushing our PC and it needs 600W. Our PSU is rated at 80% efficiency. Here’s what it’s really drawing from the grid:

600W / 0.80 = 750W

Ideally, our PC will draw about 750W from the wall under load. The remaining 150W are, quite simply, wasted and usually dissipated by the PSU as heat.

 

[stage]

28 minutes ago, Mattias Edeslatt said:

@WinWX

 

That is not how the efficiency of a PSU works. If a PSU is rated for 650 W it delivers 650 W to the system, but with 80 % efficiency it draws 812 W from the wall to deliver the 650 W

 

 

https://www.tomshardware.com/reviews/psu-buying-guide,2916-3.html

 

Yes, this is totally correct for draw of the wall. But the 80% rule is a general rule that applies to all continuous loads  (all electric appliances  and electricity), in this case PSU. It states that only up to maximum of 80% of the total rated output should be used continuously. Having it used over 80 or even worse, near max load is not good for the longevity of the unit. There is no headroom left.

[WinWX]

20 minutes ago, stage said:

Yes, this is totally correct for draw of the wall. But the 80% rule is a general rule that applies to all continuous loads  (all electric appliances  and electricity), in this case PSU. It states that only up to maximum of 80% of the total rated output should be used continuously. Having it used over 80 or even worse, near max load is not good for the longevity of the unit. There is no headroom left.

does that mean I shouldn't use the 650W PSU with my current setup and the RTX 3070 TI because it'll be using approximately 83%, and maybe a little more in some cases? The conclusion I'm drawing here is that it will work, but it won't be good for the PSU in the long term, am I right? If so, do I risk any other component?

[WinWX]

2 hours ago, Pixelfie said:

RTX cards often have spikes that are way above TDP for a few ms. So that could make it go above 650w. 650 might be enough but 750w would be better if possible. Also Seasonic had issues with these power spikes a while ago. I think it's fixed now but if you own the PSU for some time already it may be worth checking if yours is affected by this.

can you please link a reference of how big those power spikes are

[stage]

15 minutes ago, WinWX said:

does that mean I shouldn't use the 650W PSU with my current setup and the RTX 3070 TI because it'll be using approximately 83%, and maybe a little more in some cases? The conclusion I'm drawing here is that it will work, but it won't be good for the PSU in the long term. Do I risk any other component?

This is only at the worse possible situation where you draw max power for long time. You need to be running some heavy cpu and gpu benchmarks to reach the limit.which will be rare when using your PC for every day tasks and gaming. The manufacturer has that 750 wat recommendation for a reason so your system stays stable no matter what for sure. It might work fine with 650w especially good one, but better to be on the safe side.

[Guest]

3 hours ago, WinWX said:

Hey all, I just got a new EVGA GeForce RTX 3070 Ti FTW3 ULTRA GAMING (which I haven't installed yet) and according to the EVGA website, it mentions a minimum 750W PSU is required. Using PCPartPicker, I've created my build with the new video card and all the remaining parts, including the Seasonic FOCUS GX-650, 650W 80+ Gold. According to that, the build consumes 515W plus 23W of the water pump that wasn't included (538W total), so why a 750W PSU is required? Should my 650W PSU be enough?

You have the PSU.  You have the graphics card.   Why not at least try it?

 

Worst case scenario:  The PC shuts down during a game.

 

[Pixelfie]

40 minutes ago, WinWX said:

can you please link a reference of how big those power spikes are

Really depends. For example someone at Seasonic tested an RTX 3090 (rated for 350w) and got a 550w spike.

Quote

I had a chat to Seasonic, they let me know that in their labs they have seen RTX 3090 transient loads spike to north of 550W before the power limits kick in and pull them back down.

https://www.reddit.com/r/hardware/comments/k5lgm4/psa_3090_3080_transient_load_spikes_north_of_500w/

 

Just Google RTX 3000 spikes and you'll see what I mean. From what I could find it seems like the 3070 Ti isn't affected as much as other cards such as the 3090. I would just try it and see if it works. If it works and you're still worried about it getting near the 650w total power try undervolting the card, that usually helps reduce power consumption (I reduced mine by 30%: 100w > ~70w)

[WinWX]

1 hour ago, jonnyGURU said:

You have the PSU.  You have the graphics card.   Why not at least try it?

 

Worst case scenario:  The PC shuts down during a game.

 

Oh, I thought something worst could happen, like breaking a component or something.

The video card arrives Wednesday, I'll give it a try and let you all know

[Juular]

15 hours ago, stage said:

Most of them will run between 80 to 85% efficiency. So 80% out 650 is 520

No, it's not how it works.

[Jeppes]

12 hours ago, stage said:

Yes, this is totally correct for draw of the wall. But the 80% rule is a general rule that applies to all continuous loads  (all electric appliances  and electricity), in this case PSU. It states that only up to maximum of 80% of the total rated output should be used continuously. Having it used over 80 or even worse, near max load is not good for the longevity of the unit. There is no headroom left.

Not really no. Most quality psus run fine in even in hotbox tests on reviews with over 100% loads. You are basing your assumptions on those ancient garbage psus where 500W was 400W for 12V + other stuff.

[freeagent]

I have that GPU, my system running F@H draws 640w from the wall from what I saw.. hwinfo64 say the GPU is doing 330w under 3D load. Figure another 220w for the rest of your rig and you are close. My system is overclocked though..

[Elisis]

On 2/8/2022 at 8:28 AM, stage said:

Having it used over 80 or even worse, near max load is not good for the longevity of the unit. There is no headroom left.

This is a total myth. Good PSUs will be designed to be used at 100% capacity for their expected lifetime.

[stage]

2 hours ago, Elisis said:

This is a total myth. Good PSUs will be designed to be used at 100% capacity for their expected lifetime.

NEC rules and design practices are myth yes. And so are the minimum recommended requirements from the manufacturer it seem.

[Juular]

22 minutes ago, stage said:

NEC rules and design practices are myth yes. And so are the minimum recommended requirements from the manufacturer it seem.

What the safety code for residential wiring in US has to do with consumer PSUs exactly ?

[nuke7]

Every detailed PSU calculator recommends around 600W - 650W Gold should be fine, I have EVGA 650W GT gold, and I'm gonna use this with 5700x and 3070ti. If you don't push all the components to 100% power use at the same time, there shouldn't be a problem. Techpowerup recommends a 600W PSU.

[Bagzie]

Threads a year old bud.