I've recently run a Memtest on my computer which have 2 x 4gb DDR3 RAM sticks due to a lot of MEMORY_MANAGEMENT bsods. The result showed 4 errors in a run of 10,5 hours (8 passes) so clearly something is wrong. I then ran a Memtest with only one of the sticks plugged in to figure which one is causing the errors. But now I can't seem to reproduce any errors with only one RAM stick. Is that even possible? What do you suggest that I do to pinpoint what exactly the error is? Thanks in advance.
4 errors in the course of 10 hours isn't necessarily indicative of bad ram. For example, it could be a bad power supply that can't handle dramatic changes in input voltage.
Realistically, when you have bad ram it is a repeatable problem. it won't work one time and not another. I'd start looking for other culprits.