REALLY odd PSU problem

[Markfw]

OK, first, my friend has an A7N8X Deluxe motherboard (and all the rest hardware) that had a Fortron 700 watt PSU in it for like 5-10 years, I forget, lets say 9 years. Working fine. They left it on all the time. The other day they had to shut it down to move it, and it would not boot after being moved 20 feed. So they bring it to me. The fans start, but at WAY lower speed than they should. So I take out the PSU and hook it up to my Corsair HX750. Boots like a charm. So I order a Corsair TX 650 V2, and it comes in. I hook it up, now the fans boot at the correct speed, but no post. WTF ? So I hook the 650 up to an old AMD dual socket motherboard with 2 Opteron 244's and a GTS250 video card. Works perfect. The PC has 2 hard drives and 2 optical, but even with all drives totally unplugged, still no post at all wuth the 650, no beep, but fans and light work. Try the 750 again, and bingo. And my kill-a-watt under the 750 says 118 watts at full load using OCCT on the A7N8X.

So, to summarize, both Corsair mid level PSU's work on the Dual socket Opteron board, but only the 750 will boot the A7N8X Deluxe.

Any ideas ????? This is the oddest PSU problem I have encountered in my 28 years of messing with PC hardware.

 

[tweakboy]

Something might of happened to the BIOS. Put all bios defaults , and see if you get post. gl

 

[VirtualLarry]

What is the +5v amperage on the 650? Is it below 25A?

 

[Markfw]

What is the +5v amperage on the 650? Is it below 25A?

30 amp

Did I say that the whole system took 118 watts at full load using the 750 ?

 

[TemjinGold]

Return the 650 and get another HX750?

 

[Markfw]

Return the 650 and get another HX750?

$70 AR vs $130 ? By friend does not have the money.

 

[VirtualLarry]

30 amp

Did I say that the whole system took 118 watts at full load using the 750 ?

Yes, but Athlon XP rigs draw power off of the +5v rail, not the +12v rail. Well, many of them anyways.

It was much more important to have a strong +5v rail back then, than a +12v rail.

Edit: Try connecting some +12v case fans, or HDDs, to the 650 and see if that helps. I'm wondering if the minimum +12v load isn't being met.

 

[Markfw]

I have tried with no HD's and just cpu fan, and with everything, no change. One case fan I could disconnect maybe

 

[Markfw]

OK, so I got in a Seasonic M12II 520, and it also works on the A7N8X. So do you think the TX650 is defective ? Even though it works perfectly on a server dual socket motherboard ?

 

[Obie327]

Corsair makes a pretty good psu I have a few 650 tx's myself some going on 5 plus years now. Could be a flaky board or when your pushing in the 4 pin or 20-24 pin in it's working or not. Maybe try a thermal Take psu or something else of decent quality if the second Corsair won't help the situation. I personally would not use something that new or advanced in an old system like that. Thermal take or cooler master psu will probably do the trick. I'm leaning to a legacy issue here with that old system. Good luck

 

[TemjinGold]

I'm leaning towards the +5V vs. +12V explanation here...

 

[Markfw]

decided to help my broke friend out and give them a new FX-6100 and motherboard and 4 gig ram, only a couple of hundred...

 

[TemjinGold]

You're a good man.