Random BSOD's

Check out the "Usual Causes" line at this link: BSOD Index

Next time you restart your system, repeatedly tap the F8 key just before the Windows Splash Screen shows up. This'll get you to a menu for Safe Mode. Further down the list will be an entry to "Disable automaic restart.....". Select that and let the system start. At the next BSOD the system will halt and allow you to read the screen.

You can also, from within Windows, go to Start and type in "sysdm.cpl" (without the quotes) and press Enter
In the window that opens up, select the Advanced tab, then the Startup and Recovery Settings button.
In the next window that opens, in the lower half will be a section called System Failure
Remove the checkmark from the box that says "Automatically restart" and then click OK to exit the dialog.

I'd go back and run the diagnostics again:

I suggest starting all troubleshooting with the following diagnostic tests. They'll save you a lot of time and heartache if there is a hardware failure, and you'll have the disks on hand in case you need them in the future:

H/W Diagnostics:
Please start by running these bootable hardware diagnostics:
Memory Diagnostics (read the details at the link)
HD Diagnostic (read the details at the link)
Also run the SSD diagnostics again.

Also, please run one of these free, independent online malware scans to ensure that your current protection hasn't been compromised: Free Online AntiMalware Resources (read the details at the link)

Beyond that, I'm pretty sure that this is a hardware issue, so I'd have to suggest a hardware stripdown as a last resort to determine the cause: Hardware Troubleshooting Via System Stripdown

ok so i did those tests with speedfan and memtest again but they didn't show anything noteable. I also ran the suggested malware scan.

Then today when i turned on my computer and it had been turned on for a few minutes it suddenly restarted with a weird crunchy sound. I'm not sure if i also saw it light up a bit :S

It was booting but i shut it down fast and left it because i didn't have time to look at it a the time.

Then about an hour later i tried to turn it on, but it wouldn't turn on at all. There's no response when i press the power on button.

I'm thinking the power supply is dead? But i have no clue really, could it be the motherboard?

Hoping any of you have a clue here :)

Thanks in advance

Did you also run the Hard Drive diagnostic? If so, what were the results there?

If it doesn't even turn on, the first place to check is the PSU - but don't go out buying new parts just yet as this can happen with other components (such as the mobo). Try testing the PSU with one of these links: psu testing - Google Search

Try this procedure to rule out as many components as possible: Hardware Troubleshooting Via System Stripdown

I've seen some computers at work (with bad hard drives) that you can turn on - but you won't see anything on the screen. To check for this:
- unplug the system from the wall
- disconnect both cables that run to the hard drive (data and power)
- plug the system back in and see if it'll power up to get the Gigabyte splash screen (it won't boot anywhere since you don't have a hard drive connected).

If you see the splash screen, then it's usually a safe bet that the hard drive is toast. But you'll have to purchase a new hard drive to verify this (and don't buy one just on my say so - since it can be other components causing this).

Do you mean that the PSU isn't putting any power out on those leads?
If not, try purchasing a PSU from a place that you can return it (if it's not needed) and see if that fixes the problem.

Beyond that, the hardware stripdown is the way to go.