Computer sometimes hangs(freezes).

I just recently build my PC about 6 months ago, and this problem has only been happening in the past 2 months. My PC sometimes randomly freezes not at any certain task or a certain time, i cant use my mouse, keyboard anything and have to press the reset button on my case. I tried reformatting and a fresh install of Windows 7 on my PC, but the issue still occurs. I also just bought a new SSD so i cant be the HDD issue. I also tried a memory(RAM) test and still the same problem.

Things i have done:
1. Reformat and reinstall Windows 7
2. Installed a New SDD
3. I tried a memory test
4. I have the latest drivers for everthing, (MOBO, GPU and etc.)

Is there anything i can do? I am 100% it is hardware is there any other tests i can do?

Hmm.. Since no one gave any answer, and something is better than nothing, IMHO, I will just give you some small suggestions. Make sure all the cooling's fine, especially the CPU cooler. Check to see if everything's connected properly?

Yea cooling is fine, i get 30 degrees Celsius idle for the CPU, and 40 for the GPU. Everything is connected properly, thanks for your suggestion.

I know this is off topic, but I've not been to Australia for a long time.. How's everything there? Anything major happening?
Update drivers.(Even though you mentioned that you already did that) AND make sure that your PSU's fine. I once had the exact same problem, it happens either when the PSU's not properly hooked up, or it's gone bad

I been thinking its the PSU for a while, but there is no way of testing the PSU. Do you know any tests for the PSU? I need some solid proof before i can sent it in for warranty.

hhmmm wow thats a tricky one..

try new graphics card