Dell 8400 won't boot

[bmp21]

I have had my Dimension 8400 since I bought it new in 2005. I started to get blue screens and it the screen would go black. That stopped shortly after and one night I shut it down and it wouldn't start again in the morning. My first thought was that the new PSU I put in had quit. I tested it and it was working fine. When I power it on, nothing happens. The PSU lights up and the fans come on in the case. That is about it. No hardware beeps, the troubleshooting lights are all blank, and the power button is a steady amber. Dell suggests this is a CPU issue, but I don't think the CPU is the problem. I am thinking the mobo is finished, but I am not certain. I found a nice new Intel mobo but I don't want to buy it only to find that it wasn't the issue. I am wondering if I could get some help to troubleshoot and find out the source of this problem. I just want my computer back. I tried to put in a different CPU, but the only other one I have here has the pins that go into the sockets. This 8400 doesn't have that. Any help or insight would be great. Thanks in advance.

 

[tsnor]

No way to tell from the symptoms what failed. But it's rarely the CPU.

Standard debugging is to remove parts until the system POSTs. You know it got thru the power on self test when it beeps about the missing parts.

Suggest you unplug, remove all PCI cards and all memory. Then plug back in and fire it up. It should give you the beeps that mean no memory. (There is a code to the beeps, check your doc. Or just know that if its beeping that's good). Then add the memory back one dimm at a time. If it still posts (beeps) start adding back the PCI cards. Unplug each time and give it a sec to drain power before you stick memory or cards in. Ground yourself by touching the metal of the power supply often, especially if you walk away from the PC. (yes, remove all USB, network, etc. beforehand) Good luck. Here is a good ref: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[bmp21]

Well, I found the bad stick, removed it, computer started right up and I am using it as I type this. Only running on 512MB is making it a little sluggish when it starts up, but I have ordered 4GB of new DDR2 memory. Thank you for your help. I am glad to have my old reliable computer back.

 

[bmp21]

No way to tell from the symptoms what failed. But it's rarely the CPU.

Standard debugging is to remove parts until the system POSTs. You know it got thru the power on self test when it beeps about the missing parts.

Suggest you unplug, remove all PCI cards and all memory. Then plug back in and fire it up. It should give you the beeps that mean no memory. (There is a code to the beeps, check your doc. Or just know that if its beeping that's good). Then add the memory back one dimm at a time. If it still posts (beeps) start adding back the PCI cards. Unplug each time and give it a sec to drain power before you stick memory or cards in. Ground yourself by touching the metal of the power supply often, especially if you walk away from the PC. (yes, remove all USB, network, etc. beforehand) Good luck. Here is a good ref: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

Well I installed the 550W PSU again, and boom. Same problem again, although this time there are no beeps when I remove everything, and the power light is back to a steady amber colour. Can you please help me? It was working great until I tried to put the 550W back in.

 

[bmp21]

Well I feel stupid. I forgot to plug in the CPU pwr. I now have 550W rather than 350, and my 2GB of RAM is fine. I am extremely relieved. Thank you for your help tsnor.

 

[tsnor]

Outstanding. Hope it gives you another few years. The 8400 was a beast in it's time.

 

[bmp21]

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