New rig powers up only for 1/2 second, PSU is good

[LockeOak]

New rig just arrived today:

ASUS P55D-E Pro motherboard
i7 860, stock HSF
*eVGA 460 GTX
Patriot DDR3 1600 3x2GB RAM
*OCZ ModStream 700W PSU
OCZ Vertex 2 40GB SSD
*3 120mm case fans
*Antec P180

*Part of previous system, known to be functional.

When pressing the power button on the case, the fans (CPU and case) jump for a split second (less than a full revolution), but the system does not proceed. No POST, no beeps, nothing. Same result on pressing the MemOK button on the motherboard. I've removed everything non-essential and I'm down to the CPU, 1 stick of RAM and keyboard/mouse, no change. I've re-seated the CPU, cleared the CMOS and tried multiple RAM slots. The standby power LED stays on. The CPU LED lights up for the split second the system is powered. The PSU was in my last system and was working there earlier today. At this point I suspect the motherboard, it was an open box purchase. Any ideas?

 

[Old Hippie]

I wouldn't care if it worked at last reboot, I'd be swapping power supplies because the symptoms indicate it's a likely problem.

 

[Dangman]

Try a different PSU and see if that's actually the cause. If not, it's more than likely the mobo then since it is an open box.

 

[LockeOak]

Try a different PSU and see if that's actually the cause. If not, it's more than likely the mobo then since it is an open box.

That appears to be the problem. Using another PSU seemed to work. I have no idea why the PSU that I've been using for about two years would not work in this new system, I didn't even take it out of the case. Unfortunately the other PSU that I have is an Antec 550W model I intended for a lower-power machine for the family, I don't think it will be enough to handle an i7, 460 GTX SLI, HDD, SDD, sound card and DVD drive. So much for the budget.

 

[Dangman]

That appears to be the problem. Using another PSU seemed to work. I have no idea why the PSU that I've been using for about two years would not work in this new system, I didn't even take it out of the case. Unfortunately the other PSU that I have is an Antec 550W model I intended for a lower-power machine for the family, I don't think it will be enough to handle an i7, 460 GTX SLI, HDD, SDD, sound card and DVD drive. So much for the budget.

Yeah, you're looking at a new PSU. I recommend this PSU:
$90 - Corsair 650TX 650W PSU

 

[LockeOak]

Bah. I must have been mistaken... switching the PSU doesn't seem to help. Seeing as one PSU was working yesterday and the other is brand new I'm thinking it's a motherboard issue, need to dive into the Asus forums now.

 

[LockeOak]

Well, I figured it out,it wasn't the motherboard or the PSU, but a power cable. As I was building a new system and moving the old system to a new case I had two PSUs. Between them I had a lot of 8-pin to 6-pin PCI-E cables lying around and since they all looked the same I used one from the wrong PSU to my video card, the sockets were identical but the pin layout was not the same (but of course without course inspection it was impossible to tell). Not using that cable and using my old video card it works well, but unfortunately I think I may have fried my new eVGA GTX 460: it won't POST, hangs at the VGA check. I guess I have to RMA it now.

 

[Markdek]

Well, I figured it out,it wasn't the motherboard or the PSU, but a power cable. As I was building a new system and moving the old system to a new case I had two PSUs. Between them I had a lot of 8-pin to 6-pin PCI-E cables lying around and since they all looked the same I used one from the wrong PSU to my video card, the sockets were identical but the pin layout was not the same (but of course without course inspection it was impossible to tell). Not using that cable and using my old video card it works well, but unfortunately I think I may have fried my new eVGA GTX 460: it won't POST, hangs at the VGA check. I guess I have to RMA it now.

I've seen this happen to several people recently...silly but easy mistake.