Newly Built PC won't boot?

cooper795 · 20 Apr 2011 at 17:53

So, I've put all the parts into my new PC, but it won't boot when I press the power button.

It comes on momentarily, the fans begin to spin and a couple of lights come on on the mobo, but it quickly cuts out after a second or so. Are there any common reasons for this that I could look into? As I genuinely have no reason as to why this is happening or how to solve it.

If there's anything that would help you to solve the problem like pics etc. then I will provide!

Thanks

RJC · 20 Apr 2011 at 17:57

Please list full spec

Some things you can try: Is the 8 pin for cpu power connected.
Memory in the correct slots, some boards wont boot if they are not in certain positions.
Try a CMOS reset.

Tediore · 20 Apr 2011 at 17:58

Could be a faulty PSU. I had a very similar problem where I got lights on the motherboard and everything, but it just wouldn't do anything. A friend of mine had the same problem where it would boot and then just die, and his turned out to be a faulty PSU as well.

I can't really think of anything else that would cause a sudden shutdown like that, but as a precaution, I'd double check everything is plugged into the right place, seated properly etc.

Hopefully someone more in-the-know can clarify, but I don't see why it'd be the RAM or anything like that assuming they're in the right slots, as surely it should try and POST and fail/hang than do a sudden shutdown?

cooper795 · 20 Apr 2011 at 18:01

Spec:

i5 2500k with corsair A50 cooler

Gigabyte P67A-UD4 (Socket 1155) DDR3 Motherboard **B3 REVISION**

XFX Black Edition 650W Modular PSU

2 5850s in crossfire

OCZ Special OPS 4GB (2x2GB) DDR3 PC3-12800C8 1600MHz Dual Channel Kit

Western Digital Caviar Blue 500GB SATA 6Gb/s 16MB Cache - OEM (WD5000AAKX)

RAM is definitely in correct slots, I'm so confused

Tediore · 20 Apr 2011 at 18:08

Is the PSU powerful enough? What is it's output?

cooper795 · 20 Apr 2011 at 18:14

Tediore said:
Is the PSU powerful enough? What is it's output?

Whoopsie, edited it in

RJC · 20 Apr 2011 at 18:18

PSU more than enough, what slots is the ram in, as sometimes they need to be in 2nd & 4th from the cpu.

Do you have both power connections going to the gpu's and have you checked the cpu power socket as mentioned previously.

cooper795 · 20 Apr 2011 at 18:22

RJC said:
PSU more than enough, what slots is the ram in, as sometimes they need to be in 2nd & 4th from the cpu.

Do you have both power connections going to the gpu's and have you checked the cpu power socket as mentioned previously.

RAM is in slots 1 & 3, and the GPU's came boxed with 2 cables each som both have been plugged into the PSU, and checking the CPU socket now.

Curio · 20 Apr 2011 at 18:22

I've had this happen more than once over the years and it's usually one of three things - bad PSU, bad motherboard, something shorting somewhere (in my case it was a rogue screw that had got wedged against the motherboard). Assuming you've got all the power cables plugged in correctly, It won't be the CPU, RAM, hard drive or video card.

I would say bad PSU is the most likely contender.

cooper795 · 20 Apr 2011 at 18:25

Curio said:
I've had this happen more than once over the years and it's usually one of three things - bad PSU, bad motherboard, something shorting somewhere (in my case it was a rogue screw that had got wedged against the motherboard). Assuming you've got all the power cables plugged in correctly, It won't be the CPU, RAM, hard drive or video card.

I would say bad PSU is the most likely contender.

Actually I remember I lost a screw in the case earlier, and assumed that it'd just dropped on the floor, maybe that could be it. The only thing is I can't find the damn screw :mad:

Tediore · 20 Apr 2011 at 18:29

My vote is still for the PSU as well. Myself and a friend have both had similar problems. Do you have another PSU you can test with? Would you be able to DSR it and get another? If you're outside DSR you need to be sure what the problem is otherwise you'll be charged for the return.

The PSU is more than powerful enough, and you say you've checked the RAM, so a sudden shutdown sounds like a power delivery problem.

stulid · 20 Apr 2011 at 18:31

Why are you using the cables supplied with the 5850's?

The psu has four 6pin pci-e which will be powered by another rail.

Tediore · 20 Apr 2011 at 18:31

cooper795 said:
Actually I remember I lost a screw in the case earlier, and assumed that it'd just dropped on the floor, maybe that could be it. The only thing is I can't find the damn screw

Hmm, best to get the motherboard up really, just to be sure. I had to re-wire mine about 3 times, so I feel your pain

cooper795 · 20 Apr 2011 at 18:31

Tediore said:
My vote is still for the PSU as well. Myself and a friend have both had similar problems. Do you have another PSU you can test with? Would you be able to DSR it and get another? If you're outside DSR you need to be sure what the problem is otherwise you'll be charged for the return.

The PSU is more than powerful enough, and you say you've checked the RAM, so a sudden shutdown sounds like a power delivery problem.

The thing is I'm no longer so sure that I've actually put all the cables in correctly. Its my first time doing this so I guess I'll have to check them all before I jump to any conclusions about the PSU.

cooper795 · 20 Apr 2011 at 18:38

stulid said:
Why are you using the cables supplied with the 5850's?

The psu has four 6pin pci-e which will be powered by another rail.

Not entirely sure what you mean stulid.

So I shouldn't be using these cables at all? Why did they come with the cards then :confused:

skylineboy · 20 Apr 2011 at 18:39

cooper795 said:
The thing is I'm no longer so sure that I've actually put all the cables in correctly. Its my first time doing this so I guess I'll have to check them all before I jump to anh conclusions about the PSU.

Take a photo of cables your using.
take a photo of motherboard so we can see and check.

take the motherboard out of the case, remove all cards and turn upside down. Connectors etc. This will remove the possibility of it being the screw you mention. Then rebuild outside case on the motherboard box to make sure it's not shorting on case. Have you tried separate sticks and different ram slots?

stulid · 20 Apr 2011 at 18:43

cooper795 said:
Not entirely sure what you mean stulid.

So I shouldn't be using these cables at all? Why did they come with the cards then

look at the psu cables, you will see two cables come out of the PSU, each has a 6pin or a 6+2pin pci-e, and in the bag of other cables will be the same(either 2 6pin or 2 6+2pin)

The card comes with the 4pin molex to 6 pin adapters for weak/crap psu's

Tediore · 20 Apr 2011 at 18:48

cooper795 said:
Not entirely sure what you mean stulid.

So I shouldn't be using these cables at all? Why did they come with the cards then

If you're talking about molex - PCI-E, they're only for people who have older PSUs that don't have the required cables. Best to use the 6 pin cables provided with the PSU. If it's a modular PSU, make sure you plug the second lot of cables into the right ports on your PSU.

As for the cables, it's easy enough to not push them in far enough, so best to just make sure they're all plugged in properly, and that the CPU is seated properly etc. before you think about returning anything.

SouthEastBlue · 20 Apr 2011 at 18:55

Assuming you haven't cable tied it all in, it might be worth taking out the motherboard, using 1 graphics card, 1 hard drive, and 1 stick of ram then plug it all in while the motherboard is rested on top of something non conductive and try and boot it outside the case.

Having a loose screw knocking about somewhere could be causing some kind of short if it's caught under the motherboard or on something else.

cooper795 · 20 Apr 2011 at 19:18

Found the loose screw, still not working though, I'm going to follow the guide on this site rather than the one I was already using. If its still not working after that I'll post some pics on here.