[SOLVED] RX 6900 XT With Corsair CX750M Risks?

What do you guys think of this situation?

  • Best case scenario: the PSU is fine, don’t worry unless something goes wrong.

    Votes: 0 0.0%
  • Second-best case scenario: do some testing to make sure all is well.

    Votes: 0 0.0%

  • Total voters
    2

erik62905

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Hey everyone,

Yesterday I helped a friend pick out parts for a new build at Micro Center. We found some insane deals, notably a PowerColor RX 6900 XT Red Devil for $650 open box. Obviously I had them spring for that card; that is just insane. However, they were on a set budget, and in order to make things work I had them go with a Corsair CX750M. I was and am still 99% sure this power supply will be fine for their needs, but I don’t want them to face any potential issues long-term.

Brief specs:
  • GIGABYTE B660 Gaming X AX
  • Intel Core i7 12700 (non-K)
  • 32GB (2x16) 3200MHz DDR4
  • PowerColor RX 6900 XT Red Devil (BIOS switch set to OC)
  • Two M.2 SSDs
  • Two HDDs (they already had these)
  • Corsair CX750M 80+ Bronze
My reasoning for this power supply being OK was that they only plan on using the rig for games. With that, I assumed the most power the computer would need was less than 750W. The GPU under full load is around 320W average, and the CPU is around 60W in a gaming scenario. I know the GPU has transient spikes up to ~450W, but only for very short periods so I thought all would be well. The only major immediate issue to me is that the PSU came with only TWO 8-pin PCI-e connectors, and the GPU has three. I used both cables and daisy-chained one of them. I didn’t expect this, as the PSU is labeled with inter-compatible CPU and PCI-e connectors. I thought the PSU would come with three PCI-e cables but instead it came with an extra CPU cable. I know the reference RX 6900 XTs only have two 8-pins, so I think all is fine, but this is a custom AIB partner card so I’m a little weary.

Now, for any suggestions you guys may have: know that my friend is not very tech-savvy, so suggestions such as undervolting the GPU are out of the question unless I go over to their house. Likewise, they will be doing zero overclocking or really anything beyond using the computer as normal. They just plug it in and use it.

I posted a poll with the different outcomes of the situation that I can think of. What do you guys think of this situation? Right now I believe we are under the “best-case” scenario, but please tell me if I am wrong. (Edit: the reason returning the PSU is a “worst-case” scenario is because my friend and I live a solid 30 minutes away from Micro Center, and my friend does not have a car to drive themself. This would be a major hassle). Any further insight is greatly appreciated, and thanks all :)
 

Lutfij

Titan
Moderator
I'd pick out a higher wattage unit to have as headroom...also the CX would be the lowest cut off point for a PSU in Corsair's tier of PSU's. I'd look into a higher pedigree unit in tandem with the higher wattage, to have peace of mind.
 
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DRagor

Illustrious
Eh. Typical scenario - "great deal on power hungry GPU so let's take it and skimp on PSU!" I don't think you did help your friend. IMO bronze PSU are good up to about 3060/6600xt level, anything higher then that and you want better level PSU. Of course the wattage should be enough, but wattage is not the whole story.
 

--SID--

Estimable
The only major immediate issue to me is that the PSU came with only TWO 8-pin PCI-e connectors, and the GPU has three.
That's not an issue. Corsair cables are decent enough to use one single cable and one cable daisy chained. The more major issue is that the PSU has a double forward topology on the primary and can not react fast enough to the powerspikes of the GPU. For GPUs like a RX 6900 XT you definitely need a PSU with a more modern topology, called LLC. All PSUs in Tier A of this list comply with that.
 
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erik62905

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I'd pick out a higher wattage unit to have as headroom...also the CX would be the lowest cut off point for a PSU in Corsair's tier of PSU's. I'd look into a higher pedigree unit in tandem with the higher wattage, to have peace of mind.
Thank you very much for the info. My friend just told me they had a random game crash where the whole system locked up. I’m assuming the gpu tried to boost really high and didn’t get the power it needed which crashed the game. I told them not to play any taxing games until we work this out over the weekend. I found an EVGA SuperNova 1000 GT 80+ Gold PSU at Micro Center so we will probably get that… unless you have any problems with it?

Thanks again,
Erik
 

Lutfij

Titan
Moderator
Scroll down to Minimum System Power requirement...you'll have your answer. I'd add a little more to that number...again for peace of mind.

As for the GPU you spec'd out for your friend, you need to understand that Powercolor's Red Devil range of GPU's are like the cream of the crop of AMD cards whereby they're overclocked like there's no tomorrow, to which they also draw a lot of power.
 
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erik62905

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That's not an issue. Corsair cables are decent enough to use one single cable and one cable daisy chained. The more major issue is that the PSU has a double forward topology on the primary and can not react fast enough to the powerspikes of the GPU. For GPUs like a RX 6900 XT you definitely need a PSU with a more modern topology, called LLC. All PSUs in Tier A of this list comply with that.
I’m glad I have enough tech background to understand what you just said. That is one of the nerdiest sentences I’ve ever read in my life. Thank you though, I appreciate it! And thank you for providing a link.

In order of price, I found:
Edit: removed RM850x
MSI MPG A1000G ($160)
Corsair RM1000e ($180)

What PSU do you think I should have my friend get? I’m thinking the MSI 1000 watt, or should I have them spring for the RM1000e which might be slightly better than the MSI regarding fan noise and overall quality? I’ll leave the verdict to you.

Thanks again,
Erik
 
Last edited:

erik62905

Reputable
Jan 17, 2018
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Eh. Typical scenario - "great deal on power hungry GPU so let's take it and skimp on PSU!" I don't think you did help your friend. IMO bronze PSU are good up to about 3060/6600xt level, anything higher then that and you want better level PSU. Of course the wattage should be enough, but wattage is not the whole story.
stay mad
 

erik62905

Reputable
Jan 17, 2018
179
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4,715
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Scroll down to Minimum System Power requirement...you'll have your answer. I'd add a little more to that number...again for peace of mind.

As for the GPU you spec'd out for your friend, you need to understand that Powercolor's Red Devil range of GPU's are like the cream of the crop of AMD cards whereby they're overclocked like there's no tomorrow, to which they also draw a lot of power.
Thank you for that last part especially. I am not very well versed in AMD AIB parters, so I’ll need to do my research. I would have loved to get the card my friend got, but I don’t have the money for it right now. Still sitting on a GTX 1080 atm…
 

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