My gx620 diagnostic lights say: "Memory modules are detected, but a memory failure has occurred."
Brand new memory stick does not help, same happens. Is the MB broken? Any chance to repair this PC?
Thanks very much!
I suddenly got the same diagnostic code (indicators 3&4 green, beep code too) without even opening the cover, and soon found that not a single stick of either old or new memory would work at all (even though they had been working previously). It turned out the problem was a dirly DIMM socket on the motherboard. I have an ancient Dimension E310, which probably isn't quite the same ...but anyway - here's how I fixed it:
Unplug computer (no rocker switch)
Press and hold power button twenty seconds or so so tiny amber indicator light on motherboard goes completely out
Unclip and remove DIMMs
Clean DIMM contacts by putting the DIMM on a flat surface and rubbing the contacts with a _SOFT_ pencil eraser
(If it can leave scratches, or if you can see the difference, the eraser must have oxidised as it's too hard: DON'T)
Brush away all those tiny rolls of spent eraser material
Spray TV contact cleaner the entire length of every DIMM slot (with the little spray tube taped to the side of the can)
try not to make a mess,
but don't worry too much about the inevitable drips
Wait a couple minutes for the TV contact cleaner to mostly evaporate
Insert/fully-seat/unclip/remove/rinse&repeate DIMM 5-10 times in each socket
Insert/fully-seat DIMMs for real
Plug the computer back in
Turn it on - everything works now
(Contact cleaner is a whole lot cheaper and easier than replacing the motherboard, and using it doesn't preclude replacing the motherboard later if it appears it's really necessary. So try it.)