Is my Power Supply insufficient for a 7900XTX?

EchtoGammut

EchtoGammut

Supreme [H]ardness
Joined
May 7, 2007
Messages
4,127
Upgraded one computer with a RTX4090, so I moved the 7900XTX to another system that had a 2080 and now it won't load the screen (doesn't even show the BIOS screen). The second computer has a Corsair HX750i power supply and a R9 5950, which I figure should have enough power, but I after installing I got a brief flicker of something on the screen and then nothing. No errors on the MB, no apparent error lights on the GPU. I put the 2080 back in and everything boots up fine. Power issues are the only thing I could think of, but that doesn't make a lot of sense unless it does some kind of load test on boot.
 
The card was just moved from a working system, so I would be surprised if it was the card as well. The system it was moved from has a HX1000i power supply. I don't really want to take the 4090 out to test if the card still works on the old system. The only other thing I can think of is a bad cable and since I have some new cables on order for the new system I will order some 750 as well.
 
AMD is finnicky with display cables I've noticed. I had to upgrade my Displayport cables for the new card.
 
I tried DisplayPort and HDMI, but I will order a new cable, just to see if that helps because I do remember having an issue with the HDMI cable on my other machine.
 
I get by with a 700w seasonic prime psu with a 5900x and a 4080, IDK how much it pulls relative to a 7900xtx but I'd guess less. Total system usage when beating on it is in the peak of the efficiency curve for this psu.
 
My brother in law was getting shutdowns in-game with his 7900 XTX and a Seasonic Focus GX-850. Stepped up to a Seasonic Vertex 1000W and no problems since.

FWIW, I think 850W is probably "enough," but maybe the transient spikes were too much for the old girl. Expect that 850W on a ATX 3.0 unit would be enough for his rig.
 
Last edited:
I'm not sure why everyone is recommending a new PSU when he's having display problems booting. The card is not consuming much power to post and boot windows, he clearly has an issue elsewhere that a new PSU won't fix.
 
Furious_Styles said:
I'm not sure why everyone is recommending a new PSU when he's having display problems booting. The card is not consuming much power to post and boot windows, he clearly has an issue elsewhere that a new PSU won't fix.
Click to expand...

its an old 850w and kyle had issues with a 6900xt and 2 old 1kw+ units. so it is possible, maybe the gpus spikes on power up. or it could even be a loose/bad power cable...
 
pendragon1 said:
its an old 850w and kyle had issues with a 6900xt and 2 old 1kw+ units. so it is possible, maybe the gpus spikes on power up. or it could even be a loose/bad power cable...
Click to expand...
I thought those problems kyle had were stability related, he could boot just fine. But maybe I'm not remembering correctly.
 
dogDAbone said:
Go big, or go home...Wwhen it comes to powah, it's better to have it & not need it, rather than need it & not have it :D

This page is your friend: https://outervision.com/power-supply-calculator

You're welcome !
Click to expand...
Kind of. You actually lose efficiency on some higher end platinum or better power supplies when you are under utilizing it. There is a sweet spot. If you are stressing them too much or not using them to their potential, you can run in to many efficiency issues. So it’s not just a buy the biggest supply you can fit situation.

Have an idea of what you need, buy in that range with the efficiency you are willing to pay for.

Other wise you are wasting money on a supply you don’t need AND losing money to efficiency. Not so smart there.
 
I'll try reinstalling it later today, if that doesn't work a new RM1000 or reconditioned HX1000 isn't that expensive. I'll probably order it with a new OLED monitor as well... might as well give it a total refresh.
 
you can test it with the 1000w you have... or put the towers "belly to belly" and do a dual psu start up.
 
That is a possibility, I could also grab another power supply out my plastic tubs of spare parts and connect it to the card. Once the delivery guy shows up with new braided cables for the other system, I will make a decision on how lazy or ambitious I want to be.
 
EchtoGammut said:
That is a possibility, I could also grab another power supply out my plastic tubs of spare parts and connect it to the card. Once the delivery guy shows up with new braided cables for the other system, I will make a decision on how lazy or ambitious I want to be.
Click to expand...
Not recommended potentially an issue with isolated grounding.
 
I'm on a 12 or 13 year old power supply at this point, 860 watts. Might be the quality of the supply + age. 850+ is more than enough, 750 may not be especially on an older supply.
 
I don't remember how old this power supply is. It's bounced through several computers over the years and had one warranty replacement many years ago. I actually thought it was an 850W, until I loaded up the Corsair tool and it came up as 750, which is made me wonder if this CPU+GPU was pushing the max, since both are kind of power hungry.
 
EchtoGammut said:
I don't remember how old this power supply is. It's bounced through several computers over the years and had one warranty replacement many years ago. I actually thought it was an 850W, until I loaded up the Corsair tool and it came up as 750, which is made me wonder if this CPU+GPU was pushing the max, since both are kind of power hungry.
Click to expand...

You can get a Seasonic Focus 1000W with 12vhpr connector and a 10 year warranty for $119 on Amazon right now. Might be time to seek an upgrade, don't forget these big-watt GPUs have terrible problems with transient response times in older power supplies. Personally, I would not be pairing a $900-1000 GPU with a 10+ year old PSU. Just my .02.
 
LigTasm said:
You can get a Seasonic Focus 1000W with 12vhpr connector and a 10 year warranty for $119 on Amazon right now. Might be time to seek an upgrade, don't forget these big-watt GPUs have terrible problems with transient response times in older power supplies. Personally, I would not be pairing a $900-1000 GPU with a 10+ year old PSU. Just my .02.
Click to expand...
Do they still have issues with the transient spikes? Thought that nvidia largely rectified that with the 40 series.
 
Furious_Styles said:
Do they still have issues with the transient spikes? Thought that nvidia largely rectified that with the 40 series.
Click to expand...

Its still around (iirc 40-series can still see up to 1.5x spikes). I really get trying to not waste money on things you don't need, but PSU is something I never think to skimp on. The older ones I retire into "business" systems that use very little power.
 
You must log in or register to reply here.
Back
Top