Computer Randomly Turns Itself Off

I have recently upgraded to windows 10 pro from windows 7 and prior to this i have been getting BSOD and it turned out to be a faulty ram which i replaced. Now my pc runs with two different brand rams bu have same spec, ddr2 2GB 800.

anyway I have my pc connected to the 60 inch tv in our lounge and I have been getting this problem for a week now. My tv would suddenly lose signal and after 5 seconds the computer turns off. It's not a BSOD or instant shut down. This happens once or twice a day. When i turn the pc back on the lights on the pc turn on but then about 5 to 10 seconds after it shuts down again (still no signal on tv). After i turn it on a second time it turns on fine with signal coming back on instantly. This happens everytime (i have to turn the power on twice to have it actually come on and let the first time turn itself off).

I have checked the temp and its perfectly normal. I dont play games on it, just watch youtube or movies etc.

Could it be the new RAM? I haven't tried taking it out but my pc was fine up until last week (its been atleast 3 weeks since i've upgraded).

edit: only setting i remember changing is the display setting. "change the size of text, app, and other items: 150%(recommended)" this to 100%. the settings to this changes randomly after the restart or on normal boot. sometimes when i boot its on 150% even after changing it to 100% the day before. and after several hours pc would turn off and when i turn on again its on 100%.