[HELP] new kit problems - PC switching off and on

[Big G]

Hi all,

I bought all my new kit, spec as follows:

HIS ATI Radeon HD 4850 512MB GDDR3 TV-OutDual DVIHDMI (PCI-Express) - Retail
Asus P5Q-E Intel P45 (Socket 775) PCI-Express DDR2 Motherboard
Intel Core 2 Duo E8400 LGA775 'Wolfdale' 3.00GHz (1333FSB) - Retail
Corsair 2GB DDR2 XMS2 DHX PC2-6400C5DHX TwinX (2x1GB)
Akasa Ultra Quiet 400W Paxpower Active PFC ATX2.2 PSU - Black Nickel

I connected it all up as per the instructions, fitted the CPU then cooler, then fitted the the memory and then fitted the board. I plugged in the gfx card and tried to boot up on that bare setup.

The problem is thus:

After a few seconds of booting up, the PC turns itself off and then back on (not a reset, actual power off). This happens multiple times - off then on, then off then on. Eventually it starts for about a few minutes, but then goes off and on again (rinse repeat).

I've tried the following as fault finding:

- removed mobo to ensure no shorting, mounted on static proof piece of mat, no joy
- ensured all power connections plugged in
- checked cooler on CPU, fitted ok and temp about 29 degrees according to BIOS
- stripped the spec right back (no gfx, memory, hard disk), eventually running with just motherboard and CPU. Obviously it doesn't boot or get to the bios, but the random "off and on and off and on" still happens
- tried just one stick of RAM, no luck

The most luck I had was that I tried different PSU lead and that actually looked like it might have worked as it was enough for me to install windows vista and play about. I switched off the PC, fitted the mobo back inside the case and we were right back at the "on and off".

The PC doesn't crash or hang, it doesn't reset itself, there are no corrupt graphics, it just switches off and back on. I'm thinking the motherboard is screwed, or the PSU is cutting out for some reason.

Edit - i've not tried diff PSU, mobo or CPU.

Any help?

[Kryten]

Bugger.

I'd rule out the CPU, it'd continue running but wouldn't post or beep regardless of how broken it is.

Memory is the same, it'd not cause a hard power off.

Tried a bios reset? The asus boards *do* and are supposed to turn off/on again after a change to bios or settings, but this is immediate after turning on. It shouldn't cause seemingly random power offs though.

Naturally the only thing that remains and sticks out is the power supply. Assuming you've got the right 8 pin supply plugged in (there may be 2 different 8 pin connectors from the PSU, one is graphics and one is motherboard) or the 4 pin power connector in only half the 8pin motherboard connector.
400w is possibly slightly underpowered but it's a decent brand and shouldn't cause an issue, it'd be an idea to check with another if you've got one.

[Big G]

Yeah, the power connections from the PSU are:

- 2 blocks of 2 x 2 pins (so giving 2 x 4) which plugs by the CPU in the motherboard
- 1 block of 2 x 10 pins and 1 block of 2 x 2 pins which plugs by the memory into the motherboard.
- Then there is the gfx card power feed (but this still happens without the PSU).

I will go to Maplin's tomorrow I think and get a PSU to try and just return it within their "14 day" window to rule out the PSU.

The power offs do indeed seem random, they started being frequent and within a few seconds or a minute, but as the PC warmed up it started to last longer to the point I managed a full Vista install and reboot. It seemed fine, but then I plugged it all back in and it all died again. There is no pattern.

Cheers Kryt, big help - I think the PSU is the next rule out then it'll be an RMA of the mobo because the hard disk, gfx and memory all seem fine otherwise.

Do you think the CPU could be causing it?

[Kryten]

No, as I said, it would be one of the least likely issues. The only time I could think a CPU would cause that is it was very wrongly installed, and it's basically impossible to incorrectly install a socket 775 processor unless the pins on the motherboard are bent.
Never thought of getting a PSU and returning it under the 14 day (DSR) thing, a bloody good idea! At least you'll be eliminating it from your enquiries and it's a lot easier than replacing everything else in the computer to find it was something small and simple

No way you can nick the PSU out of the computer you're using now just to test it?

[Big G]

on the mobile now. Nah kryt the PSU in my spare pc is an older enermax and doesn't have all the right plugs by the looks. I could try the new akasa psu in my old pc i suppose, won't be the same load though

[Kryten]

Doesn't matter. As long as the older PSU has a 4 pin P4 style connector that'll go in the 8pin one on the motherboard. If it only has a 20 pin ATX connector it'll still fit and work. Just the graphics board it wont power but that's the least of the worries at the moment, will just help see if it works without it.

[MYstIC G]

Your original plan is probably better, if it is the PSU it seems very unwise to stick it in your older working box, just in case.

[Dark Orb Choir]

i know this is a stupid question, but have you put all/any of the little black jumpers into the mobo, and if you have are you 100% sure they are in the right place

eg clear cmos, multiplyer etc

[Big G]

Currently running the PC with my "what's the returns period for this PSU? ... 14 days you say... ?" PSU from maplin - a 500w silent affair, ATX 2.2 compliant.

Plugged it in, so far had no cut outs at all, no crashes, no reboots, no problems, nothing at all. Uptime is about 20 minutes so far, so I guess there is still time, but it's never lasted this long.

Looking like a defective PSU so far, will see how long it lasts though as I will be stress testing later.

[Trem]

Where the bloody hell have you been G?



I missed you

[VidX]

I'd say it's more an issue with the rating on the PSU rather than a possibly dodgy one. You're running some hefty kit. I wouldn't recommend less than a 650W PSU with the most recent generation of CPU and GPU hardware.

[Big G]

Originally Posted by Trem

Where the bloody hell have you been G?



I missed you

Hey Trem , you too buddy. Always about, haven't really been on FH of late though. How are you old bean?

[Trem]

I'm good ta luv but I don't like it when my jock mates go quiet

How is you, and your sister?

[Kryten]

The 400w paxpower is a decent supply, and supplies enough current to run all of that - the 4850 is quite a good card on power consumption. Still, I'd not have recommended less than 520w (ala Corsair) to be on the safe side.
Glad it appears to be working alright, I assume you can get a refund on the 400w supply anyway as either faulty or not fit for purpose.

[DaGaffer]

My swanky new PC arrived last night, and the fucking thing won't boot up at all . Its receiving power (I can see a green light inside), but absolutely no attempt to boot up. Bollocks.