just swapped the module configuration from my last post and I'm still getting a boot. This is the exact configuration that was giving me alarms about a half hour ago. Nothing has changed, pretty weird.How about 1 module of new RAM?Yep that was next... new_1 failed to boot and the alarms SOUNDED again.

I replaced it with new_2 and that has booted successfully.

I'll try new_1 and new_2 together just for kicks and then I'll START running memtest86 on new_1 like you suggested.OK so weirdly enough the computer boots up with new_1 and new_2 together.And doesn't boot with all MODULES in together. Leave new_1 and new_2 in and run memtest86 for at least 4 hours.

EDIT: I'm done for the night - good luck. OK last report, put both new_1 and new_2 in separately and this time they both booted with no problems. I just memtest it I guess and see whats up.

good night. I've just finished memtest after running the thing for 10 hours on the two new modules. It reported no errors in that time.

My computer is currently booted up with both the new modules inserted but I suspect that I will have the same problems that I had at the start of the thread. I guess I'll just have to wait and see.That's a good result from memtest86. Based on that result, I would not expect a memory problem from the new RAM. I would, however, expect that you will have problems if you add the old RAM.

May be time to stick the old memory into a drawer and enjoy the doubling of memory

My experience with XP in going from 1 GB to 2 GB was that I couldn't really notice any difference on day to day stuff. So, I would really question the incremental benefit of adding the old RAM to make 3 GB.

Do you notice any performance difference?

Let us know how the new RAM runs. So I'm back to the old problems anyway!

I left the new RAM in after memtest and it worked fine for 3 reboots before the same problem I described in my OP occurred again. I took the modules out and re-inserted them but it made no difference.

So I've given up on them and reverted back to the computers origional 2x 512mB configuration.

I'm all out of ideas again and looking for help please!!?After new_1 failed to boot, I was surprised: a) that it worked with new_2 and b) that the combination 'passed' memtest86. (Interesting aside on memtest86, memory never really 'passes' completely because memtest86 can't test all possible memory combinations; so, a 'pass' is a probabilistic pass; but, a fail is a Fail!)

Anyway, I would RMA the RAM to Corsair. I think that you bought a matched set so return both modules. But, check with Corsair - simply tell them the system would not boot or run with the RAM. Get the RMA number and instructions before sending the RAM back.

Another thing to consider - I know that you originally contemplated having 3 GB of RAM (old + new). If that is still what you want, please purchase additional new RAM.

Please let us know how you make out.