New PC - PSU conundrum

Greboth

Greboth

Greboth

Soldato
Joined
6 Aug 2010
Posts
5,818
Location
Birmingham
Hi everyone,

I'm hoping for some advice with a new build as the issue has me stumped. I built the new PC and it wouldn't post with the debug light showing a CPU error. After some testing, using the PSU from old PC the new one would post and using the new PSU, my old PC wouldn't post. Easy - DoA PSU. So I sent it back and received a replacement.

Plugging the replacement PSU in to the new PC and it still won't post. Again, plugging in my old PSU and it will post. Now the confusing part; plugging the replacement PSU in to my old PC and it works.

So;
Old psu & old PC - works
New psu & old PC - works
Old psu & new PC - works
New psu & new PC - doesn't work

The first round nothing worked with the PSU so I was happy that it was the issue. This time though, there's nothing consistent and I can't think of a cause or where to start trouble shooting such an issue.

Specs;
Old PC
Ryzen 2700x
ASUS X470 Crosshair
4 x 8Gb 8 Pack RAM
Inno3D RTX2080
Corsair RM850x

New PC
Ryzen 3600XT
MSI B550M Pro-vdh
2 x 8Gb Corsair Vengence
nVidia Quadro FX
Corsair RM650x
 
The B550 doesn’t support the 2700x though the X470 does support the 3600XT.

I was trying to avoid CPU swapping as it’s a lot of faff and I’m not sure what it would tell me given the 3600XT works in the B550 board when using my 850W psu. So I was hoping for some ideas that might explain the strange behaviour.
 
tamzzy said:
3600xt + x470 + new and old PSU

If this works then dodgy new mobo
Click to expand...

I can understand the logic of your methodology, the cpu and the motherboard at the only components that have always been tested together so it makes sense to test them apart. Though, even if it does work as you say, I'm still struggling to see how it is the mobo as surely a broken mobo is a broken mobo irrespective of psu.
 
Greboth said:
I can understand the logic of your methodology, the cpu and the motherboard at the only components that have always been tested together so it makes sense to test them apart. Though, even if it does work as you say, I'm still struggling to see how it is the mobo as surely a broken mobo is a broken mobo irrespective of psu.
Click to expand...
This is certainley odd that it works apart from the diffrent psu which you replaced. Try updating the bios on the motherboard i know its total stab in the dark but worth a try. Otherwise swap psu over 650w is enough for a 2080 i no it doesnt sort the root cause .
 
Greboth said:
Though, even if it does work as you say, I'm still struggling to see how it is the mobo as surely a broken mobo is a broken mobo irrespective of psu.
Click to expand...
Well, clearly something doesn't work.
You have a fully functional old system, so it would make sense to test each new part individually to isolate the defective component.

If I may quote sir Arthur Conan Doyle "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."
 
Greboth said:
Hi everyone,

I'm hoping for some advice with a new build as the issue has me stumped. I built the new PC and it wouldn't post with the debug light showing a CPU error. After some testing, using the PSU from old PC the new one would post and using the new PSU, my old PC wouldn't post. Easy - DoA PSU. So I sent it back and received a replacement.

Plugging the replacement PSU in to the new PC and it still won't post. Again, plugging in my old PSU and it will post. Now the confusing part; plugging the replacement PSU in to my old PC and it works.

So;
Old psu & old PC - works
New psu & old PC - works
Old psu & new PC - works
New psu & new PC - doesn't work

The first round nothing worked with the PSU so I was happy that it was the issue. This time though, there's nothing consistent and I can't think of a cause or where to start trouble shooting such an issue.

Specs;
Old PC
Ryzen 2700x
ASUS X470 Crosshair
4 x 8Gb 8 Pack RAM
Inno3D RTX2080
Corsair RM850x

New PC
Ryzen 3600XT
MSI B550M Pro-vdh
2 x 8Gb Corsair Vengence
nVidia Quadro FX
Corsair RM650x
Click to expand...
Have you tried just the CPU power cable and the 12 pin motherboard power connected for the new system and new PSU?

might be a bad connection with one of the other power connectors (I had a faulty SATA power cable that stopped my new system from POSTing)
 
Take the new system out of the case
Set motherboard with cpu and cooler on cardboard box with nothing else connected
Connect new PSU and test
 
You must log in or register to reply here.
Back
Top Bottom