Hello all,
Please help. I just upgraded my Dell deminsion 9100 2.8ghz pentium D with 4GD ram and a new Nvidia 9500 graphics card. All was working great. then I went to turn on my PC a week later and nothing would happen. I unplugged the PC and waited 10 min. and plugged back in. After that it would begin to boot, then in about 5 sec. would imediately shut off, with no beeps or sounds. I replaced the existing 375w PSU with a new 400w PSU. and still having the exact same problem. so I gues i just waisted money on the new PSU. Agreen led glows on the mother board when pluggen in. I also unplugged my hard drive and tried to boot, got same problem. I also checked to make sure none of my usb hubs were damaged. please help, any suggestions. Nathan

You get the same issue if the HDD is unplugged? Have you tried a different HDD?

If by HDD is refering to my Hard drive, then yes I did unplug it and try to boot. still did not work. However i did not try to boot with another hard drive.
Nathan

If it's doing the same thing regardless of whether the hard disk is connected or not it may be worth trying a different one. Are you able to open up the bios?

As you can run a disk check from there and that would help us locate the issue.

I tried to boot with or without the hard drive, still did same thing, I took out all my upgrades and checked for a short, found nothing, put all back in and did same thing. Changed power supply still did same thing. unplugged all USB ports and dick drives to make sure there was no short in those, comp. still did same thing. symptoms: when I try to boot, shuts down in 4 seconds with no beep or nothing just shuts off. thanks for the help, please continue to send suggestions! Nathan

Try swapping back to the older RAM, if you still have it. If the BIOS can't find any healthy RAM to uncompress in, I'd expect that it'll sit there doing exactly nothing, maybe not even a beep code.

The other possibility is that you jarrred the heatsinking loose on the CPU. Make sure that's seated right and making good contact. Also check the power-supply connectors to the motherboard -- press them in firmly to make sure they're making good contact.

The problem with Dell is they ship their computers with insufficient power supply. I think the 375 Watt PSU may have fried the mainboard. A 400 watt psu barely provides enough power for a P4 1.8ghz. A Cd/Dvd multi drive also requires a lot of power.
Get a 500 watt psu and try it. If nothing turns on then you could have a fried mainboard or ram or graphics card.

I unplugged my graphics card, still did same thing, I took out all the ram, and it did start beeping when I tried to boot up, but the beeps were just to let me know I had no ram in the pc. I did reset the heat sink to the processor and tried, it still just shut down after 3 sec. I checked all connections, I even took out and re installed the power supply. If the mother board was fried, it would not even start to boot right? anyone have any more suggestion? Thanks all for the help! Nathan

I suggest you put all the old stuff one bit at a time, like the old ram then graphic card, back into the computer and try to start.

If there is a green light on the mainboard then the graphic card is okay. It might be the Ram. Take one out and tell us the specs of it and one of the old ones. You might be using different mhz

Hmm I'm still putting my money on HDD, if it powers up then shuts down it would suggest that it was looking for a boot device but was unable to locate one.

You would get the same issue if your HDD cable had come loose, you also said that you get the same issue regardless if the HDD is connected or not?

Is there anyway you can try another HDD? Or do a HDD check in the BIOS?