Warning, long post I'm trying to cram in as much info as I can think of as I go. As per title I have been experiencing multiple BSODs since installing 2 additional RAM modules and a SSD in my laptop. My first thought was the SSD so i removed that and reinstalled Windows 7 on the original HDD, the BSODs continued :-( I have tested each stick of memory individually in multiple slots with no errors showing in memtest, I am currently running a test with all the memory installed, and as of now there are no errors (test is still running, and I'm planning on leaving it overnight) Assuming this test also passes what else can I look for to resolve these crashes, it's becoming very frustrating not knowing what is causing the problem. Some of the errors reported by the BSODs have been: Driver IRQL not less or equal modification of system code or critical data structure detected System service exception Page fault in nonpaged area And my favourite; "A problem has been detected" (thanks, windows ) The crashes seem to occur more frequently when first loading windows and just before/after logging in, and if the system survives the first 15-20 minutes without a crash it can almost always survive for many hours of use, even in heavy use such as games etc. without crashing, this "surviveability" carries over reboots, making reproducing the crash very difficult - it only seems to crash if it has been off for a while, but even then the randomness doesn't guarantee a crash. The only other variable I can think of is the reinstall of windows, so maybe a software or driver issue? I obtained all the latest drivers and grabbed all windows update, so am unsure. System specs (going from what I can remember atm): Dell XPS L702x Intel i7 GeForce 555M 3GB 250GB HDD 120GB OCZ Agility 3 SSD (not installed atm) 4GB (2x2gb) DDR3 1333mhz ram (original ram) 8GB (2x4gb) DDR3 1333mhz ram (new ram, tried with and without the old ram installed at the same time) Windows 7 64bit Anymore info needed just ask and I'll try my best to provide it.