System won't POST

[Bat123Man]

Hi,

I am building a second computer for the kids from spare parts I have lying around from my previous upgrade. I bought a brand new Corsair PSU (HX620) and am worried that it may somehow be incompatible with my old mobo.

The system :
Asus P5N-E SLI (not running it in SLI)
Corsair HX620 PSU
4 GB RAM
Intel Core2Duo 6420
80 GB SSD
eVGA 8800 GTS 320 MB

I installed the new PSU, and connected the 24-pin connector and the 12v ATX (4-pin). I have tested the 12v to be sure it is working by disconnecting it and trying to boot. They system comes on for 1 second, and then powers off. When I connect the 12v ATX, the system appears to come fully on, the green light on the mobo is on, and all fans are operational. However, there is no beep, nothing comes up on the monitor.

I have disconnected everything but the mobo (pulled graphics card, disconnected SSD and DVD drives), and still nothing. All fans start up including the CPU fan, the green light on the mobo comes on, it looks like it is working, but again, no POST.

So I started over. Pulled everything out, and this time ensured that the standoffs were only connected to the 6 screw holes (there were 2 extra standoffs I had left in just to provide additional support). I remember reading that metal standoffs can cause a short and prevent a POST. Still no dice. I have 2 8800's from my old system which I used to run in SLI, although I am only planning on using one of them. So I switched them out in case one was bad. Same thing. I made sure the SLI selector was set for single card, and that the 6-pin power cable was connected to the 8800.

Am running out of ideas. One thing I could try (but am reluctant), is to hook up that mobo to my new computer's PSU to make sure it can POST. It is the only other 24-pin PSU that I own. Lastly, this mobo ran for years. I haven't pulled the RAM or the CPU, they are still firmly in place from my last upgrade when I bought a new mobo + CPU + RAM, so they should still all work. The only change is the Corsair PSU.

Thanks,
BM

 

[Bat123Man]

Found some posts about this combo, seems others have had issues with Corsair HX series PSU and the P5N-E. I don't think it necessarily means they are not compatible as I am sure there have been issues with every possible combination of PSU and mobo, but just wanted to add that I have tried pulling all but 1 stick of RAM, and it still won't POST.

I'll try using my Enermax 620W from my main system with the P5N-E, it is all I can think of at the moment. Maybe if I simply swap PSUs, then both systems will be happy. Pretty reluctant to do this as the last thing I want to do is screw up the main system, but other than that, totally out of ideas.

Anybody think of anything else worth trying?

Thanks,
BM.

 

[crashtech]

Does that mobo have an integrated speaker? You might need to plug one in to hear beep codes. Do you have a different video card to try? One obvious thing, is that card thing flipped the right way for single GPU operation?

 

[SolMiester]

You havent used the GPU 4 pin plug for the CPU 12v 4 pin in error have you?, they are supposed to be different shapes, however, I have seen it done before!

 

[Bat123Man]

You havent used the GPU 4 pin plug for the CPU 12v 4 pin in error have you?, they are supposed to be different shapes, however, I have seen it done before!

No, the PSU is modular. Only the 24-pin and 4/8 pin 12V ATX come out of the unit, the rest have to be plugged in on both sides.

Also, I finally bit the bullet and pulled my Enermax 620W out of the main computer. I hooked it all up, and..... no POST. So now at least I know it is not the Corsair PSU. Seems like maybe the mobo is fried. I am having a hard time believing that however, it worked perfectly for at least 4 years before I upgraded it. When I pulled it out, I stored it in an anti-static bag, and it has been sitting on a shelf in the dark ever since.

I put the Enermax back in the main comp (including the 4/8 ATX connector), and that computer started right up (so at least I built that one properly ;-).

@Crashtech - speaker is hooked up, or at least the cable is correctly connected to the pins on the mobo, it hasn't made a beep yet since it never POSTs. I have ensured the SLI selector is correctly in Single GPU mode, and tried it in Dual just for fun (no diff). I have two eVGA 8800's, I have tried both of them. I remember one got a little bit wonky and started causing crashes, unfortunately I didn't make a mark on it so I could tell them apart at the time (the cards are identical). A couple of months before I upgraded mobos, I removed one of the 8800's and stopped using SLI (the gain in FPS wasn't that great anyway).

So I am stumped. I even pulled out 3 of the 4 sticks of RAM, no change. Then I set it up in dual-channel with 2 sticks in total (instead of 4). Same. Dunno what else to try........

Thanks,
BM.

 

[Bat123Man]

Other things I have tried :
- Cleared CMOS by pulling the battery and resetting the jumper to 2-3 for 10 seconds. Then set it back to 1-2, and put the battery back in.

- Pulled the 12v ATX connector. Computer shuts itself off as soon as I turn it off if the 12v is not connected. That tells me the 12v is working.
- Pulled the PCI-E power cable from the vid card. Computer issues a load annoying "eeeeeeeeeeeehhhhhh" when I try to boot. That tells me the PCI-E power connector is working.
- Tried all sort of different RAM combos (1 in, one dual-channel pair, 3 in, all 4 in, etc.). Never seems to make a difference.
- Keep switching the DVI connector (there are 2 on my vid card) in the hopes that it will suddenly display something. The button on the LCD goes blue when I switch, but then turns Orange again indicating it has no signal.

 

[crashtech]

Well, I'm stumped. You've done everything I would have done, pretty much all that is available to you. One last effort might be to test the motherboard out of the case, in the slim chance something in the case is touching the bottom of it and shorting to ground.

 

[Bat123Man]

Ah, it must be fried. I had already thought of the shorting possibility as I did deliberately left some standoffs just for support, but then removed all the extra ones trying to fix this problem. I just pulled the mobo out of the case, and ran it on top of a newspaper. Same problem. All fans start, the green light is on, no beep, nothing on the LCD.

OK, I think it is fried. That blows. It doesn't really make a lot of sense to buy a used 775 mobo, I may as well get a cheap G2020 with mobo. Ho hum, this project was supposed to ONLY use parts I already had. I already dropped some cash on a 620W modular PSU, so now I'll be on the hook for mobo + RAM + G2020.

Thanks,
BM.