|12 GB of RAM? Why? That's a 64 bit version? When systems freeze, I think of three things:|
1. Diagnostics, 2. Diagnostics, 3. Diagnostics.
There's no way to tell what's going on w/o making sure all your system settings are correct in BIOS and OS, correct drivers installed, as well as making sure your system is clean of malware etc. If those are all OK, I'd test everything: HDDs, Optical ROMS, RAM, PSU, look at the motherboard for any bulging capacitors, make sure the RAM modules are fully seated in their slots, look for loose or cracked connection and power cables, look for loose CPU and/or heatsink, noisy or hard to turn fans which indicate bad bearings.
Is the system clear of all dust & debris?
If you can't test 12 GB of RAM, test it in smaller chunks by removing some RAM if possible.
The last PC that I saw freeze , and by freeze I mean it freezes while in the OS (it's much more rare with newer better systems like than in the old Windows ME/9x days), was an XP system w/ an Intel board ---- the whole CPU/heatsink/fan assembly was a tad loose from the motherboard and wasn't fully seated. I'm assuming it was the ahem, "technician" who looked at her system prior to me. He also installed the main case fan backwards. Never assume anything.
Just another stupid saying...