750W PSU enough for 7950X3D + 7900XT?

[256shadesofgrey]

Hello,

 

I'm building a new PC but trying to reuse as many parts from the old one as possible. And in particular I'm wondering about the PSU. I currently have a Corsair RM 750x 80+ Gold that I bought in 2017. The new setup will have an AMD 7950X3D CPU and probably a 7900XT GPU.

 

When I set the configuration in pcpartpicker, it said that it estimates 650W, and AMD says that officially 750W is recommended with the 7900XT. Combined with the fairly high 80+ Gold rating of my PSU and the fact that the 7950X3D is quite efficient for a CPU in its class it does sound like it should be sufficient, but I'm wondering if I missed anything.

[Agall]

7 minutes ago, 256shadesofgrey said:

Hello,

 

I'm building a new PC but trying to reuse as many parts from the old one as possible. And in particular I'm wondering about the PSU. I currently have a Corsair RM 750x 80+ Gold that I bought in 2017. The new setup will have an AMD 7950X3D CPU and probably a 7900XT GPU.

 

When I set the configuration in pcpartpicker, it said that it estimates 650W, and AMD says that officially 750W is recommended with the 7900XT. Combined with the fairly high 80+ Gold rating of my PSU and the fact that the 7950X3D is quite efficient for a CPU in its class it does sound like it should be sufficient, but I'm wondering if I missed anything.

Minimum recommended for a 7900 XT is an 750W PSU, so I'd generally recommend at least meeting that. Given its an older 750W, you're probably best off buying a new PSU. I'd expect a 10-15% loss in capabilities for a PSU over 4-5 years, so considering that, you're practically at sub 700W.

 

7950x3D is at most a 155W part under a full synthetic load. In gaming, its not far off of the 7800x3D in my experience, being about 55W.

 

Would you be fine on an old 750W PSU? Probably, but should you? I personally wouldn't if you're about to drop +$1500 on new hardware. PSU failures can be relatively safe but can also be catastrophic.

[podkall]

3 minutes ago, Agall said:

Would you be fine on an old 750W PSU? Probably, but should you? I personally wouldn't if you're about to drop +$1500 on new hardware.

isn't RMx A tier PSU?

[256shadesofgrey]

3 minutes ago, podkall said:

isn't RMx A tier PSU?

It is according to this thread, that's why I picked it back then.

[Agall]

Just now, podkall said:

isn't RMx A tier PSU?

Regardless of its 'tier', its still a power supply. Over speccing in the long term is a good idea for maximum efficiency and mitigating wear while maintaining sufficient headroom.

 

One of the rules I follow being 50-65% expected load for peak efficiency therefore lowest temperatures. Example being my system with a 1200W power supply which could likely run off a 750W power supply, but likely not for long, given my draw from the wall regularly exceeds 700W.

 

ASUS Power Supply Units | Republic of Gamers | ASUS United States

 

This is a tool I'll reference too. As mentioned, the 750W recommendation is probably fine, but having a 6 year old PSU changes that. What also changes that is if you're overclocking.

[podkall]

2 minutes ago, Agall said:

given my draw from the wall regularly exceeds 700W.

I see, op has 7900 XT which also can transient spike quite high

[Agall]

4 minutes ago, podkall said:

I see, op has 7900 XT which also can transient spike quite high

 

AMD Radeon RX 7900XTX and RX 7900XT Review - One giant step forward and one step sideways | Page 11 | igor´sLAB (igorslab.de)

[256shadesofgrey]

Looks like I'm buying a new PSU. Thank you.

 

The funny thing is, back when I bought it, I thought it was already overkill, but the way that the GPUs have been going lately, I guess there is no such thing. 

[Agall]

8 minutes ago, 256shadesofgrey said:

Looks like I'm buying a new PSU. Thank you.

 

The funny thing is, back when I bought it, I thought it was already overkill, but the way that the GPUs have been going lately, I guess there is no such thing. 

GPU wattage requirements have practically doubled for mid-high tier systems. There's also power spiking issues that can trip over current protection, but that seems to be mostly limited to RTX 3000 or RX 6000 series top end GPUs (GA102 or Navi21 GPUs).

 

Compared to that 7900 XT chart, here's an RTX 4090 with the 133% power target I generally use (unless it's really hot then I go down to a 90% power target, because comfort).

 

 

Dug this up, for a GTX 1080ti.

[Jeppes]

2 hours ago, Agall said:

GPU wattage requirements have practically doubled for mid-high tier systems. There's also power spiking issues that can trip over current protection, but that seems to be mostly limited to RTX 3000 or RX 6000 series top end GPUs (GA102 or Navi21 GPUs).

 

Compared to that 7900 XT chart, here's an RTX 4090 with the 133% power target I generally use (unless it's really hot then I go down to a 90% power target, because comfort).

 

 

Dug this up, for a GTX 1080ti.

You do realize there is a difference between a 50ms peak and constant load? It is specced 750W for constant loads, not for short lasting peaks.

 

And it being an rmx, its not really a 750W when new. Even if you count in some aging, the likelyhood of it being capable for less than 750W in first 10 years is miniscual and you can rma it if that happens.

[Agall]

9 minutes ago, Jeppes said:

You do realize there is a difference between a 50ms peak and constant load? It is specced 750W for constant loads, not for short lasting peaks.

 

And it being an rmx, its not really a 750W when new. Even if you count in some aging, the likelyhood of it being capable for less than 750W in first 10 years is miniscual and you can rma it if that happens.

I agree, and those peaks can be a limitation as I discussed. I haven't seen widespread OCP issues with RX 7000 series, but power spiking does seem to still be an issue to some degree. Nvidia has seemed to figured it out with how insanely consistent the draw of the RTX 4090 is, as demonstrated.

 

I personally wouldn't rely on the reliability and then support of a 7 year old product with at minimum $1500 worth of new hardware, regardless of if its still 'in warranty' and 'in spec'. That's my personal choice and I'd rather have a still known good spare power supply than burn it out running it at its limit.

 

To quote my first post on this thread: "Would you be fine on an old 750W PSU? Probably, but should you? I personally wouldn't if you're about to drop +$1500 on new hardware. PSU failures can be relatively safe but can also be catastrophic."

[Jeppes]

12 hours ago, Agall said:

I agree, and those peaks can be a limitation as I discussed. I haven't seen widespread OCP issues with RX 7000 series, but power spiking does seem to still be an issue to some degree. Nvidia has seemed to figured it out with how insanely consistent the draw of the RTX 4090 is, as demonstrated.

 

I personally wouldn't rely on the reliability and then support of a 7 year old product with at minimum $1500 worth of new hardware, regardless of if its still 'in warranty' and 'in spec'. That's my personal choice and I'd rather have a still known good spare power supply than burn it out running it at its limit.

 

To quote my first post on this thread: "Would you be fine on an old 750W PSU? Probably, but should you? I personally wouldn't if you're about to drop +$1500 on new hardware. PSU failures can be relatively safe but can also be catastrophic."

Running at its limit? Its not even close. You can say what you want about ltt and their testing but they did a good job countering the psu alarmists testing a 4090 with 650W with 0 issues. People also seem to forget that going amd 8-core or 12/16-core 3D is already a -100W recommendation when compared to high end intel cpus.

 

And quality units like corsair rmx are never close to the advertised wattage. You can run +200W constant loads with that unit like reviews show. So even if you have lost 200W with aging, what i highly doudbt, you would still have 150-250W extra for that pc.

[Agall]

4 hours ago, Jeppes said:

Running at its limit? Its not even close. You can say what you want about ltt and their testing but they did a good job countering the psu alarmists testing a 4090 with 650W with 0 issues. People also seem to forget that going amd 8-core or 12/16-core 3D is already a -100W recommendation when compared to high end intel cpus.

 

And quality units like corsair rmx are never close to the advertised wattage. You can run +200W constant loads with that unit like reviews show. So even if you have lost 200W with aging, what i highly doudbt, you would still have 150-250W extra for that pc.

RTX 4090's power draw is entirely dependent on how you've configured it and what application you're running. It can average 250W of draw or 600W of draw, entirely dependent on those variables. Obviously if you ran it at a constantly lower TDP, you can proportionally lower its 'minimum recommended power supply', being something the manufacturers themselves set.

 

We'll just have to agree to disagree since we clearly have different operational modes on power supply headroom and limits. OP can decide on their own what they prefer.

 

Once again, I'll quote my first post. "Would you be fine on an old 750W PSU? Probably, but should you? I personally wouldn't if you're about to drop +$1500 on new hardware. PSU failures can be relatively safe but can also be catastrophic."

[Kinda Bottlenecked]

22 hours ago, 256shadesofgrey said:

Hello,

 

I'm building a new PC but trying to reuse as many parts from the old one as possible. And in particular I'm wondering about the PSU. I currently have a Corsair RM 750x 80+ Gold that I bought in 2017. The new setup will have an AMD 7950X3D CPU and probably a 7900XT GPU.

 

When I set the configuration in pcpartpicker, it said that it estimates 650W, and AMD says that officially 750W is recommended with the 7900XT. Combined with the fairly high 80+ Gold rating of my PSU and the fact that the 7950X3D is quite efficient for a CPU in its class it does sound like it should be sufficient, but I'm wondering if I missed anything.

 

Warranty on those units is 10 years. I wouldn't change the PSU. Those things don't lose operational capacity as they age that easily when you buy something of quality. I another PSU that's 12 years old and its running that same as it did on day 1. 

 

I would safely run those things till the warranty is over.

[256shadesofgrey]

I ended up ordering a new PSU (Corsair HX1200) right after I made my previous post, it should be arriving tomorrow. But If I had waited a day longer and saw the post that I now marked as the solution, I wouldn't have. A bit of wasted money, but it works within my budget, so not a big deal.

 

Thanks to everyone for their input.