Yes, I have read "PERFORM THESE STEPS before posting about POST/boot/no video problems!"
This is a long post (sorry) but it's important that you follow the chain of events.
This concerns a computer which was built in 2003. It has a problem and, for reasons I won't bore you with, I'm trying very hard to bring it back to life to finish a project. This effort has been going on for months. Here's why:
The heart of the system was an Asus P4B533 motherboard, 2GB of DDR RAM (2 sticks), an Intel Pentium 4 2.8 GHz processor, and an Antec True430 power supply.
Several months ago while the computer was off (ie. PSU plugged in and turned on, but computer "off") I heard what sounded like 4 fire crackers going off. After a bit of sniffing, I took out the PSU, opened it up, and sure enough there were 4 electrolytic capacitors that had exploded. Apparently this PSU has a history of doing that.
They don't make that PSU any more, and after consultation with Antec tech support about what would be the best replacement option we agreed it would be the Antec TP-550C. So I ordered one. When it arrived, I installed it in the case, plugged everything in and turned on the PSU. The green power LED on the MoBo came on. When I pushed the power button the fans started up but everything shut down after 4 seconds. No beeps. No POST.
I then removed all the cards, all the hard drives and all the peripherals to see if the power would stay on with nothing but the MoBo, CPU and memory. Same result. On for 4 seconds then off.
I removed the round lithium battery, and replaced it with a new one. I bought a new memory stick. Same result.
I removed everything from the case. The MoBo is now sitting on a non-conductive surface with nothing touching it other than the 20 pin power connector and the 4 pin CPU power connector.
My next conclusion is that something on the motherboard must have blown. Maybe when the power supply blew it sent a spike downstream that fried something. I did a visual inspection and couldn't see anything obvious. So I went on eBay looking for a replacement Asus P4B533 mother board. The closest I could find was an Asus P4B533-V, which appeared to be in good condition. I researched the differences between the two, and the only significant one was that the "V" model had built-in video (doesn't matter to me because I'm using a video card anyway). But it had the same Pentium 4 CPU socket and the same chipset, I put in the "new" mobo, transferred the CPU over (yes, I redid the thermal paste and everything), carefully checked all the jumpers and DIP switch settings, and once again powered it up with only the CPU and RAM in place. This time it ran for half a second and shut off. New memory, old memory, no difference.
Having already replaced the motherboard, I thought that maybe the CPU was damaged. I bought a brand new P4 in a sealed box and put that in. No difference.
At this point I had replaced the motherboard, the CPU, the RAM and the power supply and neither system would stay on more than a few seconds (the old system for 4 seconds, the new one for less than 1 second). I concluded that the problem must be with the brand new PSU since that's the only thing in common. Antec agreed and gave me an RMA to send it back. I got a replacement. I tried it. NO CHANGE AT ALL.
I am not an expert, but have been dealing with computers for decades and this is the most annoying/baffling thing I've ever seen. Does anyone have any suggestions before I throw up my hands in total defeat? Is there something about this power supply that is incompatible with these motherboards? Am I missing something obvious?
Thanks for any help!
This is a long post (sorry) but it's important that you follow the chain of events.
This concerns a computer which was built in 2003. It has a problem and, for reasons I won't bore you with, I'm trying very hard to bring it back to life to finish a project. This effort has been going on for months. Here's why:
The heart of the system was an Asus P4B533 motherboard, 2GB of DDR RAM (2 sticks), an Intel Pentium 4 2.8 GHz processor, and an Antec True430 power supply.
Several months ago while the computer was off (ie. PSU plugged in and turned on, but computer "off") I heard what sounded like 4 fire crackers going off. After a bit of sniffing, I took out the PSU, opened it up, and sure enough there were 4 electrolytic capacitors that had exploded. Apparently this PSU has a history of doing that.
They don't make that PSU any more, and after consultation with Antec tech support about what would be the best replacement option we agreed it would be the Antec TP-550C. So I ordered one. When it arrived, I installed it in the case, plugged everything in and turned on the PSU. The green power LED on the MoBo came on. When I pushed the power button the fans started up but everything shut down after 4 seconds. No beeps. No POST.
I then removed all the cards, all the hard drives and all the peripherals to see if the power would stay on with nothing but the MoBo, CPU and memory. Same result. On for 4 seconds then off.
I removed the round lithium battery, and replaced it with a new one. I bought a new memory stick. Same result.
I removed everything from the case. The MoBo is now sitting on a non-conductive surface with nothing touching it other than the 20 pin power connector and the 4 pin CPU power connector.
My next conclusion is that something on the motherboard must have blown. Maybe when the power supply blew it sent a spike downstream that fried something. I did a visual inspection and couldn't see anything obvious. So I went on eBay looking for a replacement Asus P4B533 mother board. The closest I could find was an Asus P4B533-V, which appeared to be in good condition. I researched the differences between the two, and the only significant one was that the "V" model had built-in video (doesn't matter to me because I'm using a video card anyway). But it had the same Pentium 4 CPU socket and the same chipset, I put in the "new" mobo, transferred the CPU over (yes, I redid the thermal paste and everything), carefully checked all the jumpers and DIP switch settings, and once again powered it up with only the CPU and RAM in place. This time it ran for half a second and shut off. New memory, old memory, no difference.
Having already replaced the motherboard, I thought that maybe the CPU was damaged. I bought a brand new P4 in a sealed box and put that in. No difference.
At this point I had replaced the motherboard, the CPU, the RAM and the power supply and neither system would stay on more than a few seconds (the old system for 4 seconds, the new one for less than 1 second). I concluded that the problem must be with the brand new PSU since that's the only thing in common. Antec agreed and gave me an RMA to send it back. I got a replacement. I tried it. NO CHANGE AT ALL.
I am not an expert, but have been dealing with computers for decades and this is the most annoying/baffling thing I've ever seen. Does anyone have any suggestions before I throw up my hands in total defeat? Is there something about this power supply that is incompatible with these motherboards? Am I missing something obvious?
Thanks for any help!
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