I'm hoping someone might have some thoughts on what to do. My system wont boot. I hit the power button, and then the PSU, CPU, chipset, and case fans spin up, but a second after spinning up the fans stop and the boot ends. The led power light on the motherboard stays illuminated the whole time. If I unplug the PSU or turn the power switch off and then back on then I can press the power button and get the same brief spin up. If I hold down the power button for 10 seconds and then press the power button it will then perform this brief spin up. If I dont do any of these things I can keep pressing the power button and nothing happens.

I've unplugged all the drives and nothing changes. I pulled the CMOS batter and verified good amps from it.

Prior to this boot issue I had some problems with a new (Feb 2008) WD Caviar drive I was using to store media (not the OS drive). Windows reported it as having too many disk errors so it dropped it from Sata 3.0 to 1.5. Also it had a few NTFS errors that required running checkdisk. And I had some BSODs. After one crash on restart BIOS reported a SMART error. I ran WDs drive tools on the drive and it reported no errors with the drive and the drive worked fine after that error. Also, my system disk access on both OS and media drive have seemed to degraded recently.

This is alot of info but I'm hoping it might be of help in diagnosing the problem. My thoughts are motherboard or PSU. I think I should get a new PSU and see if that works. If that doesn't work I figured I'd replace the motherboard. But I found out that socket 939 is dead. That being the case if it is not the PSU I'd build a new PC but have also considered at the same time fixing this PC as a backup (I'm really hurting business wise not having my PC). I dont want to spend alot money if I have to fix this rig and dont need sizzling performance. Any recommendations on a new, relatively inexpensive MOBO, CPU, and memory setup to replace my existing components? Again, I'd also be building a new PC for higher performance but I would want decent performance. And I should add I'm not a gamer. I'm a programmer using my PC to run lots of apps, programming and graphic design software .

Thanks for any thoughts!

System:
Purchased 8/2005
CPU: AMD Athlon 64 3700
Mobo: ASUS A8N-SLI Deluxe 939
PSU: ENERMAX EG565AX-VEFMA2.0-SLI 535W
Memory: CORSAIR XMS 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 400 (PC 3200)
HD: WD Raptor

This is going to sound interesting, but reseat the motherboard (take it completely out of the case and reinstall it) and make sure there are no standoffs under the board (all of them should come up through the screw holes in the board).

The motherboard generally will not turn its green LED on if its faulty, and a faulty PSU generally will not provide any power whatsoever. So I am not sure on your diagnosis. I had that very motherboard give on on me, but it would not boot AT ALL and no power light was on.

Asus provides 3 year warranties on all motherboards, so you are still under warranty. Might want to try and RMA it just to eliminate that as an issue.

Let's see if we can fix the problem before we look to upgrade. However, you can upgrade to a nice dual core system now for around $500. If you want more info send me a PM.

Ah, so the MOBO is under warranty. In all my frustration I didnt even think to check. The PSU is too. So if it did happen to be either one I should be able to get it replaced. That is a bit of a relief.

I'll try your suggestion tomorrow morning.

I'd love to fix this as this was the first PC I built myself and have been proud of my effort.

also check that the heat sink on the CPU is firmly in place and that the CPU fan connector is in correctly. Some mobo's have a safety feature which may be kicking in.

also check that the heat sink on the CPU is firmly in place and that the CPU fan connector is in correctly. Some mobo's have a safety feature which may be kicking in.

I pulled the mobo from the case. I have no cards, devices or buttons attached. I just have both power plugs 24pin and 4pin connected to the board nothing else (the cpu fan is still connected). I used a pen to make a brief connection between the power button pins and I still got the same behavior. I unlatched the fan/heatsink and relatched it with no change. Is there anything else I can do in regards to testing whether the issue is with the CPU and any safety features that might be stopping the boot?

If there is nothing else I can test then the next step would be for me to hook up the new power supply that should arrive today. If it doesnt work I'll try to RMA the board.

If I get this right, your system was working OK for a while, then had a few malfunctions, and now will not boot at all. Sounds like progressive degradation of something.

I would check the capacitors on the mobo and/or PSU. A short time ago there was a rash of problems with capacitors that broke down in 1 to 3 years. Typically one or more would swell and later burst open. Look for cylindrical cans the appear to have bulged ends or worse. If that's the problem they should be covered by warranty provisions.

Yes, basically worked great for 2 1/2 years. Then 3 months ago I had a problem with a SATA drive. I just assumed and accepted that the drive went bad. The new drive worked fine at first, but then had problems. Interestingly I didnt seem to be having problems with the main OS drive. I had wondered if it was my PSU. It is a 550W Enermax so I think it should be able to handle my system and did for 2 1/2 years. The only other thing I've really added is an external USB drive but is has its own power.

Eventually I started having some BSODs and now no boot. It actually progressed to worse once the no booting started happening. The system would spin the fans up on a boot for 10 seconds, or 20 seconds. One time after it started not booting it even booted and ran for an hour. I had been working on the problem so I thought I had actually fixed it. I was able to monitor fan speeds and voltage in the bios for that time and everything showed good numbers. Now, it wont spin the fans for more than 1 second.

Good idea on the capacitors. I checked the mobo. I had read about this problem. They seem to be fine. No brown goo, none of the heads seem to be bulging or split and the sides dont seem to bulge. I'm a little worried about my diagnostics skills with this issue. I'd love to see this problem on a real board and not in pictures to make sure I know how to spot it.

Just got the PSU. Hooked it up and it started right up. Now I have the tedious job of reinstalling and wiring up the case. But I think I'm in the clear. I'm be RMAing the PSU.

Thanks for all the suggestions!

Not entirely correct. Any motherboard LED's that are on when the computer is off, are powered by the line called "5V Standby" or "5V AUX". This is always on if the PSU is plugged into the wall and any power switch on the back of the PSU is turned on. This output (main connector, pin 9, violet wire) comes from a small power supply - usually about 10 watts or so - that is completely separate (except for primary power, of course) from the main power supply.

Learn something new everyday! Thanks jsc

So I know this issue has been resolved, but I have the same problem now. When I first put my computer together, the fans spun, on everything, even the graphics card. I just got no video at all, no response to the HDD being read either. So I took out my motherboard, kept everything plugged in for the most part. Tried to get a post.. It ended up booting up for the first time. This is a newly built computer. So anyway it booted when i took it out of the case. Came up with the no keyboard error. So I took the PS2 port and plugged it in. The computer immediately shut down. Sh*t. I knew it wasn't the psu, i tried my antec 650. With the 650 I get a fraction of a second longer spin on the fans. On the motherboard next the the PCI Xpress slot there is a green light that goes on when the machine is booting, it goes on for as long as the fans spin. 1 Second at most. I have spent a reasonable amount of money and have been very unlucky with this computer.

Specs:
MSI P6N SLI Platinum LGA 775 NVIDIA nForce 650i SLI ATX Intel Motherboard
EVGA 640-P2-N821-AR GeForce 8800 GTS 640MB 320-bit GDDR3 PCI Express x16
Kingston 2X2gig RAM
2.20 intel core 2.
Antec 500 neo

everything brand new, except video card is a year old. I have two machines, so i can switch everything out to see if each individual piece works. I did that prior to the PS2 ownage. Anyway i haven't done it again due to the tediousness of the process. let me know with any questions or suggestions. thank you.

well scratch that about two rigs working. Tried the 650 powersupply within the case of the computer that was broken. Could it be the case that is shorting out my PSU, or should i try plastic mounts for the mobo? This is so annoying taking it apart 200 times and putting it back together to no avail.