can't witch, comp crashes while gaming! help

So, recently updated my CPU and Motherboard, did fresh windows install, fresh driver installs, all that.

Problem is, now while gaming, comp will eventually crash. it's kinda a weird crash to, no error messages, no weird sounds or visual effects, screen just goes black (input stops to TV so it just changes to one of those no signal found screens) computer doesn't even turn off its still running afterwards so I have to manually shut it down and turn it back on.

This might happen after 10 minutes of gaming, or 20, it seems pretty random. I thought at first it was just the Witcher 3 doing it, so no big deal.. maybe just need a better video card. Then i started trying out grow home, well that has the same issues, and thats no where near the game witcher 3 is. I've checked critical crash reports, and the only thing that shows up is the power loss from me powering down the computer when it happens. The only thing I can think of is if its over heating, but I have speed fan installed and nothing is running too crazy hot, no hotter then before my new components.

so.. any ideas, help, would really be appreciated!

Running I7 4 GHz, windows 8.1, Geforce GTX 480, 8GB of ram.

Only during gaming? Tried reseating the CPU cooler? What are the temps you get?

Cable properly connected? The one from your GPU to TV/monitor.

Only while gaming. I've seen the GPU get up to 90C. Which is pretty high but shouldn't shut it down. I'm out right now but planning on picking up a new case fan while out. Cable is fine, had it Ll hooked up for weeks doing Netflix and stuff like that until I started gaming with it.

It's max is 100C so I wouldn't run anything heavy on it if I was you.

What about CPU temps?

So last night I put a new case fan in, and monitored the temps while playing.. It's over hearing for sure. I saw temps in the 100s. The CPU is running mid 90s. No OC, stick heat sink

90C is normal for stock CPU cooler under load.

Since when?!

OP you need to fix your cooling. Also you said your i7 is at 4GHz which sounds to me like it's overclocked.

Since it's cooled with stock cooler as he said, well actually I would reapply thermal paste just in case.

No 4k is the stock for this CPU. In going to reset the sink, and maybe lower the voltage to it as well.

I've never done the whole thermal paste thing before, always have just used the stock stuff it comes with. Not sure how difficult it is.

Hah, turns out I didn't seat the heat sink properly. The second I touched it in was like damnit, I'm a idiot. I'll partially blame it on Intel for their terrible style or heat sink tho, just give me screws

EDIT: No! No it fixed nothing! Still running over 90c after a minute of gaming. Ugh!