Today I upgraded my computer by getting a shiny new case, 2TB HDD and PSU. I clean installed Windows 7 on the Hard Drive and ever since the upgrade the computer randomly freezes. It's generally every 5 minutes or so, all the apps stop responding and then everything freezes. Th only thing that works is the mouse. So I can move the mouse around, but CRTL + ALT + DEL doesn't work. Then a few minutes later the system works perfectly fine again. I can generally trigger the freeze in explorer (Copying a file etc) or by using Firefox. I have one suspicion and I am not sure if or why it would all of a sudden make a difference. I have a dual channel motherboard with 4 RAM slots. Only 3 RAM slots are filled. Could this cause the serious instability?
Incompatible RAM has always been the source of my problems. It mostly depends on if you've put in varying RAM sticks that have differing frequencies & timings. Did you check if your RAM is compatible with your motherboard? You can just check their Qualified Memory vendors list for your specific mobo model.
If you don't have warranty to worry about, turn off your PC. Open it up and pull out the extra stick and leave the others in the correct (colour coded usually) slots. Test it, if nothings changed, you can get RAM from a similar, perfectly working computer & test it in yours.
This might be a personal preference but I like to only use all my RAM, that's for each computer, to use one brand & model. I find I get less instability that way.
Then again, if you've got a gigabyte or some other lower quality motherboard, they can cause very annoying problems (for me BIOS and video signal anomalies).
Wonder what is your HDD brand? Just asking because my previous Samsung had this weird, annoying resonance & constant sector corruption (I wasn't abusing it, was just faulty).
Wish you the best of luck. :)