PC restarts at random intervals (probably solved?!)

Can be a lot of things, try a diferent and better PSU from a friend or family.

Check motherboard if you see some anormaly like a leak from capacitator or some burn mark.

My old motherboard got a surge, still worked but was crashing radomly at times,some weeks worked fine but others not. If the motherboard is damaged, Sata ports doesn´t work properly and restart the pc

I have read your replies. Although you keep insisting it is not a temperature problem, can you post your temperature results that you have? I remember HWMonitor have a way to keep appending saving the current temperature into a text file until it is stopped or close. Use that tool, and try to CS:GO until it restarts. Then you can see the point of temperature just before it restarts.

I had similar experience. if it's a laptop, then most probably it's the temperature.

if it's a desktop, I had one time encounter a similar problem. In the end, it was resolved when I use 20-pin instead of 24-pin when connecting PSU to Mobo.

Had a problem like that a while back because of a Nvidia GPU driver. My first recommendation would be to check the Windows Event Viewer. That's how I found out the cause of my problem.

Lots of people pointing at the PSU/RAM.GPU, for obvious reasons as they are the typical troublemakers but I wanted to throw something out there that caused similar issues for me that rarely gets thought about.
There is a possibility that your case power/reset switch(es) are at fault. In this case it sounds like the reset switch is the most likely culprit. I had a bad power switch that had me replacing my PSU (thankfully under warranty) and tearing my hair out when that did nothing.

Try unplugging the reset switch from your MoBo and seeing if that stops it.

Of course it could be an issue with the MoBo's reset circuit in which case you're out of luck.

I had a similar problem, but it happened a few times a day. I wasn't really doing anything special, troubleshooting and disk/ram checks reported no issues, I cleaned the dust, reinstalled Windows, even tried replacing some of the components. I brought it to the repair shop and it took three experts four days to figure out that the reset button was stuck :D

stress test ram, cpu, gpu with some programs, see if only cs:go is unstable, if so try clean wipe of gpu drivers and install older versions, check running process, you could have running crypto miner w/o your permission that probaly crash gpu when run along with a game, idle temps will be higher.

Mine was the windows/driver updates causing some sort of compatibility error. Send it to the shop.

Check event viewer and post screens of last 100 errors (Or list them)
http://www.dummies.com/computers/operating-systems/windows-10/how-to-use-event-viewer-in-windows-10/

I think what the issue is, is your PSU is dying.

I had the exact same thing happen to me with the same symptoms last year, where my pc was shutting down randomly when not even playing games, just browsing the web. I checked my temps with HWMonitor and my temps were at 45c, so I figured it couldn't be overheating.

I then unplugged everything and removed my PSU from my case and when looking at it, it had this white paste/goo substance I noticed near the capacitors (I think) and then I don't remember seeing that white paste/goo before so I figured something had to be wrong with the PSU. I then checked my warranty and I was lucky I was still under warranty. I had a 5 year warranty on my PSU, had a year left when it did die.

I then got a replacement and so far haven't had any issues of my pc randomly shutting off, so maybe you will have to see if your PSU is still under warranty so you can get a replacement; otherwise, you will have to probably buy a new one?

http://www.tomshardware.com/answers/id-3204451/computer-shuts-turn-psu-unplugged-plugged-back-minutes.html

This is what I posted a year ago, also a thing I forgot to add that I now remember was what was odd or strange is when my pc would shut off, I actually had to unplug the PSU from the wall for like 15mins then plug it back in to even turn it back on - and it made like a clicking noise as well, maybe posting on these forums you can find someone with more knowledge to help you.

I had a similar problem once, the problem turned out to be that my Power Supply Unit wasn't fully plugged in.

i had the same problem a few years ago
had to do a bios update, after that the problem was gone
what do you have for a mainboard?

I had this problem b4 when your cpu or other part heat up system restart it self to give you warning about the part that are heating up .

Afaik, CS-GO is a CPU bound game. If I recall Z77 mobos work on 1155 socket, Intel's Sandy and Ivy bridge are not that power hungry. Also you never said what graphics card you're using. If you can't afford a new PSU right now, skip CS-GO and live PC Gaming at the edge ^^ (Just kidding).
You're probably pulling to much power on the 12v line and I don't think that PSU gives 650 watts tbh. You can try this and see If It works: disable C power states and any feature that makes your CPU to work at lower frequencies and voltages in BIOS, download that Gigabyte app that gives you 12v, 3.3v and 5v readings since you have a gigabyte mobo (Easy Tune up I think?) and check while you open certain software or browse etc.

Use the system only on lower tasks (browsing, youtube, steam OS etc) and see If you can replicate the issue while you're at It. Then play less power hungry games, then go for CS-GO.

No, but seriously what's your whole system setup? Give all the people here more info. Exact graphics card model, CPU model, number of hard drives, fans, etc. Random reboots problems are a bummer. And who knows how much time that PSU will last (how many years has been working?) You can also check how your system behaves without your dedicated GPU. Only using Intel's Integrated GPU.

Like they all said above, It's probably your PSU. But you can also look for inflated capacitors on your motherboard. That PSU might have "hurt" one of your caps. How much time you have with your whole system? When did you bought the dedicated graphics card?

Maybe Windows Crapdates is the one to blame ^^. So much damn variations.

How long have you cleaned the dust from your computer?
maybe the fans do not work. if a long time to assemble a computer - to change the thermal paste on the CPU and graphics card.
there may be bloated condensers.

it is advisable to check the memory (Memtest86) and the hard disk (mhdd or victoria). I usually use Hiren's Boot CD

Sorry about the lack of answers, girls and guys. I've been reading your comments, don't worry. I did multiple tests to find the problem on my PC. So far though, after re-installing the nvidia drivers, my PC hasn't restarted again by itself, so maybe that was the problem?! If the problem re-appears, I'll post again. ;P Thanks for your interest and your helpful comments.