New PC wont work

[Deleted]

I've recently bought a new PC. First time builder, built the PC, connected everything carefully (more or less, I dropped ~3 screws on the MB^^) and whenever I start it up, it shuts itself down after a few seconds without displaying anything and starts up again a little later, repeating this circle until I manually shut the PC down.
My spec:
8GB-Kit Corsair Vengeance Low Profile
WD Caviar Blue 1TB
Sapphire Radeon HD 7870 XT
MSI Z77A-G45
Intel Core i5-3570K
Xigmatek Gaia
Samsung SSD 840 Series (120GB)
Fractal Design Define R4
Seasonic S12II-520

What might be the issue? I've rebuilt it once yesterday, but the same thing happens again and again. Feel free to ask whatever you need to know to help me (if you can help at all), as I don't really know what is important and what isn't.

Edit: I also don't have any idea what might not work properly, as from looking at the PC eveyrthing seems to work. All the fans are fine, the mobo displays some LEDs and so on...

[chazus]

Some questions

1) Did you put the brass risers in between the motherboard and case?
2) Is the 24 pin (on the right) AND the 8 pin (on the top left) power plugged into the board?
3) Is the video card power plugged into the video card?

[Mifuyne]

another question added in after chazus;
4) Are you using your old windows install on the hdd/ssd?

[ElectricMango]

if your mobo is not properly grounded sometimes it will shut off on you

[Deleted]

Some questions

1) Did you put the brass risers in between the motherboard and case?
2) Is the 24 pin (on the right) AND the 8 pin (on the top left) power plugged into the board?
3) Is the video card power plugged into the video card?

1) Yes. But some of the screws didn't go in straight away and they're leaning a bit sideways (not the brass risers, the screws that go into them).
2) Yes.
3) Yes, but one of the 6pin connectors has PCI-E written on it (thought that suggests to put it there) and a 2pin connector comes out of the 6pin one (so the cable has 8 pins in total).

another question added in after chazus;
4) Are you using your old windows install on the hdd/ssd?

Nope, a new copy (also a new HDD).

if your mobo is not properly grounded sometimes it will shut off on you

So it might have to do with the screws not perfectly in place?

[Mifuyne]

Do you have the required power to power all the hardware?

[chazus]

1) Yes. But some of the screws didn't go in straight away and they're leaning a bit sideways.

I... want to say that... should be okay? But at the same time, stuff can be finicky. If the board is bolted to the riser properly, it may be torqueing the motherboard oddly. Have you tried running the motherboard outside the case with just the CPU and RAM? If you haven't done this, look up the NewEgg system builder videos where they do it, and try that first.

Also, have you tried running with just one ram stick at a time, in different slots?

3) Yes, but one of the 6pin connectors has PCI-E written on it (thought that suggests to put it there) and a 2pin connector comes out of the 6pin one (so the cable has 8 pins in total).

I'm assuming you mean it's a 6+2, and the port is 6, so there's just 2 pins hanging out doing nothing. If that's the case, that's fine.

[Deleted]

I... want to say that... should be okay? But at the same time, stuff can be finicky. If the board is bolted to the riser properly, it may be torqueing the motherboard oddly. Have you tried running the motherboard outside the case with just the CPU and RAM? If you haven't done this, look up the NewEgg system builder videos where they do it, and try that first.

Also, have you tried running with just one ram stick at a time, in different slots?


I'm assuming you mean it's a 6+2, and the port is 6, so there's just 2 pins hanging out doing nothing. If that's the case, that's fine.

I'll try that, thanks (no time atm but I'll come back to it this evening). And yes, it's a 6+2 connector.

Do you have the required power to power all the hardware?

I guess...^^

---------- Post added 2013-04-13 at 02:11 PM ----------

One more thing I totally forgot about: The PC doesn't just shut down, it RESETS. So after shutting down it comes back and that circle repeats until I shut it down manually. Gonna edit the OP...