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I have an asus P5B-E motherboard with four 1GB sticks of RAM. I had an E-VGA 7900GS video card installed. Last week, suddenly, the computer stopped responding and the display went dark (during normal usage). When attempting a cold restart of the machine, it would not post and instead yielded 1 long beep and 3 short beeps.

My research suggested that this was either a memory issue or a video card issue. I tried they video card in two other machines and they would not start with the card installed. I therefore ordered a new BFG 7900GT video card and installed it. Now, the computer still posts with 1 long beep and 3 short beeps.

However, now, sometimes the computer still starts up as normal and runs fine and sometimes it doesn't. Also, the BIOS and OS now only show 2.43 GB of RAM. I've tried pulling the memory out 2 at a time. When I do that, no matter what combination of 2 sticks is in there, it shows a full 2048MB or RAM. However, when all four are in there, it only shows 2.43 GB.

In addition, if I do warm restart of the computer, it posts with the normal single beep.

Any ideas or any tests I could perform would be appreciated.

EDIT:

Jut some more information. I removed the BFG card and put in an ATI Radeon card into the same PCI express 16 slot. With that video card and 4 sticks of RAM in there, the computer boots up and posts with no errors (single beep). Also, the bios now shows 3Gb of RAM, but this board never reported a full 4Gb anyway. The only thing I changed was the video card. One important thing to note is that the 7900GT requires a power supply connection whereas the ATI card does not. Could this mean the power supply is actually causing the problem and is manifesting in the form of a memory or video problem?

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Well, I tried re-seating everything a couple of times but that didn't work. So, I then tried powering on using the NVidia card with no power supply connection to it. That worked and the system POSTed correctly, but the card was running in reduced performance mode, of course. So, I then re-connected the power supply to the video card and have had no trouble in 5 days. – NYSystemsAnalyst Feb 4 '10 at 13:40
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2 Answers

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1 long, 3 short = Conventional/Extended memory failure: RAM is bad

Test various memory combinations with Memtest86+

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Bingo. Run Memtest86 (I run it from my trusty Ultimate Boot CD) across each stick of RAM for multiple passes. If all sticks pass without any errors, start testing pairs, then all 4. If any single stick reports errors, it's defective and needs to be replaced. – Russ Warren Jan 29 '10 at 4:22
I'll work on testing the memory this weekend. Out of curiosity, does the fact that having only two sticks in, no matter what combination, shows up as 2Gb, but having four sticks in only shows up as 2.4Gb mean something could be wrong with the Mobo, like the ram slots themselves? I also read a suggestion on another site that the power supply could be under-volting the RAM. How likely is this? – NYSystemsAnalyst Jan 29 '10 at 13:34
See Edit above. – NYSystemsAnalyst Jan 30 '10 at 3:52
any results from memtest86+? – Molly7244 Jan 30 '10 at 11:04
I've only had time to do one of the four sticks so far. I gave it time for three passes and it was OK for each one. The reason I'm leaning away from the memory is that changing video cards seemed to make the difference. With the ATI card, it posts just fine. With the NVidia card (which requires power), it does not post. Somehow, this seems to affect the amount of RAM detected by the BIOS as well. – NYSystemsAnalyst Jan 30 '10 at 14:07
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The problem was caused by a bad video card. Ordered a new video card (same architecture as the first) and that solved the problem.

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