Hi all, I have a problem with my PC that has been bugging me for sometime now, it seems I've tried everything I can think of but nothing helps. Before I get started I'd like to point out I'm quite computer savvy, I made my own, others for friends, and done numerous upgrades. So it's fair to say I know my way around a PC.

So, basically what is happening is that sometimes my computer just locks up and freezes, nothing responds, all audio cuts out, and the screen just stays on whatever it was just on and everything is in a standstill. No keyboard commands or anything works so I have to restart my PC using the on/off button. These freezes are completely random, sometimes it will happen 5 minutes into logging in, others it may go a couple of days without happening. But usually I'm getting one or two per day, sometimes even three. I thought I had fixed the problem last night, but alas, it froze on me 30 minutes ago. 

So what I've done, firstly I was certain it was a RAM issue, as apparently having two sticks with different timings can cause this. So I manually put in the timings, voltage, and frequency to their correct numbers and took them of 'Automatic'. Still that didn't work, so I removed one stick and ran on one, it froze so I swapped, and it froze again (I've been trying to fix it for a month or so now). I've installed a hotfix that apparently fixes the problem (The said 64 bit Windows 7 does this sometimes), but nothing, I've updated Direct X, uninstalled just about any program that people have said causes freezing sometimes, but still nothing. It should be noted that this PC is relatively new. I had made one a few years back but gutted it a few months ago and replaced almost all the parts. I installed a new CPU, Motherboard, RAM, DVD Drive, and Graphics Card.

My old specs were:
AMD Phenom II X4 810
Asus M4N78 Motherboard
2GB Corsair XMS2 (I had two 2GB sticks but one slot in the motherboard died)
MSi Radeon 4850 512MB (That was going off the deep end, also causing crashes)
Samsung 300GB Sata HDD
WD 1000GB Sata HDD
Gigabyte 420w PSU
Windows 7 Ultimate 32 Bit

I was also using a WD 1000GB External HDD, along with a Logitech wireless keyboard, Razer Krait mouse, and a Dell 17" LCD screen.

My specs now are:
INTEL Core i5 2400
Gigabyte H61M-S2PV
8GB Corsair Value Ram (Model Number CMV4GX3M1A1333C9)  
Gigabyte Radeon 7770OC 1GB
Samsung 300GB Sata HDD
WD 1000GB Sata HDD
Gigabyte 420w PSU
Windows 7 Ultimate 64 bit (I made the step up to 64 bit to fit the 8GB of RAM)

I am still using the WD 1000GB External HDD, Logitech wireless keyboard, Razer Krait mouse, and Dell 17" LCD screen.

Thanks in advance I am looking forward to see your responses.
Luke