Memory disappearing/reappearing

[crossy]

I bought (then new) Corsair Vengence Pro memory in Christmas 2010 - an 8GB kit (2x4GB) and apart from having to remove the heatsinks (carefully!) because they wouldn't fit under the cooler it's been pretty stable since, (this was before the "LP" editions of the V.Pro came out).

However, the other day I noticed that Windows 7 was reporting that 4GB of my memory was unavailable. Figured that it was probably loose in the socket, so took out the DIMM's and swapped 'em over - job done.

Alas, that "fix" only lasted a couple of days and that 4GB dropped off line. Strange thing is that CPU-Z says I've still got 2 modules (even returning the memory serial etc), and leaving the system to run for a while and then rebooting gives me back my full 8GB. I'm planning to try the other DIMM slot pair, but I'm looking for any other advice - e.g. any tool that'll help me spot a bad DIMM?

I'm hoping it's a bad DIMM, not a bad slot, as I don't mind replacing the DIMM's but replacing the mobo is a bit more of a problem.

[dannyboy75]

Have you tried Memtest 86+ ? It's an odd-sounding problem you have, as dodgy ram usually gives BSODs in my experience, rather than disappearing altogether. But Memtest would be worth a pop.

Otherwise, I guess your only option is to run one DIMM at a time, and try it in each of the two slots you normally use, to see if the issue only occurs with one particular slot, or with one particular DIMM. Personally I would've thought faulty RAM is more likely than a duff slot, but then nothing surprises me in IT these days

[kalniel]

When the LGA sockets first came in for Intel chips, a lot of people had the problem of disappearing RAM caused by bent socket pins, usually related to HSF installation and often over-tightening of retention pins. Did you disturb the cooler when changing RAM?

[aramil]

Bad dimm contact. Hopefully it's an over tightened cpu heat sink, that is distorting the board.

If not memtest each dim in the working slot (one at a time) and then retest in the suspect slot.

[crossy]

Done a good few tests (even managed to borrow some other memory modules at one point) and have proven (to myself at least) that the problem is down to a bad slot on the motherboard. So my memory module pair is now sitting in the other pair of slots and the system seems happy. Wonder why it decided to go bad after all this time...

Thanks for all the advice.

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