Help - new build fail

antasari · 4 May 2009 at 15:26

Hi everyone, I was hoping my first post for a while would be to boast about my new PC, but it turns out life's not that easy. It started well: outside the case, I could post and get into the bios. So I installed into the case and added fans and drives. But then I stopped getting any video output. I've taken everything out of the case again, and the problem remains.

Currently wired up:

PSU Corsair HX620
motherboard Gigabyte GA EX85 UD3R
i7 920
HSF Scythe Mugen 2
OCZ 3 x 2GB PC3-128000
XFX GTX 275
USB keyboard
screen

When I jump the power, the PSU fan starts fine. The eight LEDs on the board all light up. But the CPU fan starts, but cuts out almost immediately. And I get no video output. No beeps at all coming from the board.

Both the 24-pin and 8-pin power cables are in the motherboard (and have been re-fitted). The graphics card has both 6-pin cables, again both re-fitted. The 4-pin CPU fan is in the motherboard. I have tried each of the three memory modules individually, and in different slots. I have tried the graphics card in each of the PCIE x16 slots. Everything is out of the case, so there doesn't seem to be anything shorting.

What could be wrong? As I say, when I first wired everything up, I could get into the bios and the CPU temperature was reported in the low-twenties. Why would it deteriorate? Perhaps the CPU cooler has come loose somehow? (Doesn't seem like it.) Since I seem to have ruled out a memory problem, I think all I can do is try to re-fit the CPU and cooler and, if that doesn't work, RMA the motherboard?

All the components are new, and I don't have an old machine to hand that I can swap components into.

So much for the long weekend ... please help?

Edit: I have also cleared CMOS, didn't help

J.B · 4 May 2009 at 15:51

Apart from the usaul check all the cables Im stumped. Its odd that it worked outside the case.
The only thing I can think of is you put it in the case, shorted something out an now borked the mobo.

StevenRaith · 4 May 2009 at 15:55

J.B said:
Apart from the usaul check all the cables Im stumped. Its odd that it worked outside the case.
The only thing I can think of is you put it in the case, shorted something out an now borked the mobo.

Quite - I managed to mislay a screw when putting my noctua on. Thankfully I heard it rattling around under the mobo before plugging the damned thing in...

Try unplugging everthing, giving all the contacts a quick wipe with a lint free cloth, whip out the CMOS battery and flick the jumper over to 'clear' and let it all sit for half an hour while you have a nice cuppa and some Hob Nobs.. Then pop it back together outside the case with just one stick of RAM, the CPU and GPU and see how you get on?

antasari · 4 May 2009 at 16:12

StevenRaith said:
Quite - I managed to mislay a screw when putting my noctua on. Thankfully I heard it rattling around under the mobo before plugging the damned thing in...

Try unplugging everthing, giving all the contacts a quick wipe with a lint free cloth, whip out the CMOS battery and flick the jumper over to 'clear' and let it all sit for half an hour while you have a nice cuppa and some Hob Nobs.. Then pop it back together outside the case with just one stick of RAM, the CPU and GPU and see how you get on?

Yeah, I haven't tried removing the battery, just re-setting the jumper. Will give it a go.

I don't think I've shorted anything -- all nine stand-offs were in place and I'm pretty sure I never dropped anything inside ... there's nothing there now I've taken the board back out of the case but who knows. Time for that cup of tea ...

siumatfung · 4 May 2009 at 17:22

cpu fan poss not seated correctly, if you think about it when it was outside mavity would have been pulling it towards ur mobo but when u put it in ur case its sideways so the fan may be loose hence the pc starts then shuts down

antasari · 4 May 2009 at 17:52

siumatfung said:
cpu fan poss not seated correctly, if you think about it when it was outside mavity would have been pulling it towards ur mobo but when u put it in ur case its sideways so the fan may be loose hence the pc starts then shuts down

Everything seems pretty tightly screwed on ... but I'll get hold of some fresh TIM and try re-setting the CPU tomorrow. I made do with what came with the fan, but that's in the bin now.

spitzoid · 4 May 2009 at 18:01

+1 for CPU fan, although I suspect that it is the actual fan power cable that is not connected or faulty (make sure it is connected to the specific CPU FAN header on the mobo).

antasari · 4 May 2009 at 19:02

spitzoid said:
+1 for CPU fan, although I suspect that it is the actual fan power cable that is not connected or faulty (make sure it is connected to the specific CPU FAN header on the mobo).

CPU fan confirmed in the right header. I unscrewed and replaced the fan: I hadn't forgotten to fix the CPU lever down, and the TIM was fairly even over the plate but without spilling anywhere beyond the edge.

But still no joy. Will talk to the supplier about the motherboard tomorrow. I don't think I've done anything to damage it, but either way it seems the likely culprit.

StevenRaith · 4 May 2009 at 19:10

spitzoid said:
+1 for CPU fan, although I suspect that it is the actual fan power cable that is not connected or faulty (make sure it is connected to the specific CPU FAN header on the mobo).

Meh, as long as it spins it should be fine. I have nowt plugged into the fan header on my P5Q [two noctua 120mms on the Noctua HS plugged into the chassis header so I can adjust it in speedfan] and just told it to ignore the CPU header in the BIOS.

Before I did that, it gave me a warning saying there was no fan connected, hit F1 to continue; so it should still POST without it.

Even then, the Scythe Mugen should give enough cooling, evne passive, for a POST before thermal throttling kicks in.

You had a chance to try it now that you have had than cuppa, sir?

Try it without the CPU fan header plugged in, just for a few seconds. If it gives the post BEEP, then retry with the fan plugged in again. If it doesn't work, you know the fan is knackered. It won't screw teh CPU to be passively cooled for a few seconds.

A disconnected CPU fan should never cause a failure to POST. Ever.

Incidentally, I killed the fans on my Noctua cooler - it's now passive cooling - and it went from 35deg idle to a SHOCKING 39deg...so I don't think overheating would be the problem