Ok so I have a custom built computer. I made it about 4 years ago. And it had been running fine until recently. Whenever I try to run photoshop or run anything that takes a lot of memory it shuts off without warning. The green light is still on and I have to turn all power off to get it to come back on. I cleaned the heatsink. Changed RAM. Changed RAM slots. Tried reinstalling windows but when it starts going it shuts off the pc. I changed power supply. I went as far as to change video card. It's not overheating either I checked and it's at about 28 degrees (celsius) and it's set to shut off at 85. Any help would be greatly appreciated. Thanks.