Newly built PC not powering on....

Daemonic

I've just built a new pc but when i press the power button nothing happens.
I've removed all unnecessary components and tested again with just the mobo (Abit IG-80), cpu (Pentium 4), memory and using the onboard video. Still nothing happens...no beeps, the fans stay idle etc.
To eliminate the mobo shorting on the case, I removed the motherboard from the case and put it on a non-conductive surface (the box it came in) and tried powering on again, still no life.
When i plug in the power cable a single diode/led on the mobo lights up, however its not labelled so no idea what it means other than the mobo is seeing power.
Only slightly non-standard part of the build was the need for an adaptor to allow me plug my 20 pin psu connector to the 24 pin connector on the mobo.

Anyone got any ideas on what could be wrong or suggestions for trying to find the faulty component?
I don't have access to another system i can plug the parts into to test them so I'm probably limited....but any help is appreciated.

Morkin

What PSU you using - has it enough juice for that P4. I think you need to have both power connectors plugged into the mobo to get enough power for the CPU.

If the PSU is specced okay then try using a multimeter to check woth voltage on all rails.

Then the usual things as well if possible - PSU with another mobo/cpu etc.

Let us know how it goes,

M.

Deadwing

bet you a pound to a pinch of sh!t is the psu. after spending a weekend in a rage trying to figure out why my newly built pc wouldnt turn on, i finally copped on the psu was borked. Sure enough, opened it up, blown fuse in it. Bought a new one, pc was fine, and has been ever since

angelofdeath

check the power, reset, hd cables going to the mobo, i usually find that they are the main culprit because they are usually badly labeled and it's easy to put them in the wrong place

Daemonic

angelofdeath wrote:

check the power, reset, hd cables going to the mobo, i usually find that they are the main culprit because they are usually badly labeled and it's easy to put them in the wrong place

I've eliminated all those....just memory and cpu plugged in at the moment.
The original case i tried to power up with is an Artic Cooling case with a 350W PSU, does that sound too low for a P4 (3.6ghz so probably as power hungry as they get).
Just tried it with an old Q-Tec case. It also has a 350W PSU and same result, diode light comes on mobo lights up but nothing else happens.

Updated......
Just tried plugging my old mobo into both PSU's and not a flicker of power with either. Both PSUs have previously run the old setup fine....so how likely is it that one of the new components has fubar'ed the PSU's.
BTW, only mobo, cpu and memory have been connected to both PSUs.

Morkin

Try for a 450W+ PSU and make sure it's rated for P4 and A64 - they need TWO power connects to the mobo - the additional one is for the CPU.

Antec are good but you could just try one from PCWorld and drop it back within 7 days no questions asked.

Good luck,

M.

pred racer

Any time Ive had this problem its cause Ive plugged in the wire from the switch to the wrong pins on the mobo(sometimes the pin outs are very confusing, sometimes wrong) especially when the Led on the mobo is lighting.
if you have the mobo on a non conductive surface with just cpu and mem installed try shorting pairs of pins with a screwdriver normally works for me.

Endurance Man

Im running my P4 3.0ghz chip with 1gig of ram, 2 x 2500gb hdd and a dvd writer, on a 350wat codegen psu :rolleyes: . Now im probably trying my luck as its a rubbish psu but i am geting a new 1 soon. Its been running all this for a about 5months fine, but not gonna try my luck any longer

Sparky

same crap is happening to me with my new A64 rig, mobo powers for less than a second fans turn slightly and bam gone, i have to uplug the psu from the wall to get it going again, so my 2 cents is that the PSU is the problem here, ive ordered an Antec NEO480GB so that should work for me.

Daemonic

Thanks for all the responses. I'm going to source a new PSU, however i'd still like some opinion on whether plugging the mobo with CPU and memory into 2 different PSU's would cause both of them to die completely.
I would have assumed that if the PSU could not supply enough power they would not power up but would not be damaged. Does the CPU trying to draw too much power blow a PSU?
Both PSU's have since been tested with my original mobo etc. Both PSU's previously ran the old setup for a year a piece but both are completly dead now when hooked up.
If I open the PSU's up to check them, what would i be looking for?

Soundman

Really stupid question but the fuses in the IEC cables used to power the PSU's are rated correctly yes? Meaning 13A fuses. Just seems strange that the PSU's have died from under-powering the CPU/mobo combination.

Daemonic

Soundman wrote:

Really stupid question but the fuses in the IEC cables used to power the PSU's are rated correctly yes? Meaning 13A fuses. Just seems strange that the PSU's have died from under-powering the CPU/mobo combination.

I assume you are referring to the cable between the PSU and wall socket. I've used 2 different cables, both of which have been used for months/years without any problems.
I agree that it seems strange that an underpowered CPU could blow a PSU

Sparky

there could be a thermal fuse blown in the PSU for safety reasons, ive seen where PSU's capacitors have blown because of load.

Daemonic

Sparky_S wrote:

there could be a thermal fuse blown in the PSU for safety reasons, ive seen where PSU's capacitors have blown because of load.

I opened one of the PSU's and i can only see one obvious fuse, glass cylinder with metal ends. This looks fine, the wire inside looks intact.
Are there other fuses to look for. If so whats the easiest way of spotting them?

Sgtshaft

Could the mainboard be shorting? Remove it from the case and try to power it up.

Daemonic

Sgtshaft wrote:

Could the mainboard be shorting? Remove it from the case and try to power it up.

Tried that. Placed it on the boc the mobo came in and rtied powering on with just cpu, memory and onboard video hooked up.

Sgtshaft

May sound silly but did you check the bios jumper?

Sparky

Daemonic wrote:

I opened one of the PSU's and i can only see one obvious fuse, glass cylinder with metal ends. This looks fine, the wire inside looks intact.
Are there other fuses to look for. If so whats the easiest way of spotting them?

just be sure by checking the fuse with a continunity tester, or if you have a multimeter there should be a same feature aswell.


you also mentioned an adaptor to convert your 20pin to a 24 pin, could the fault be here?

smeggle

most P4 boards have two power plugs - the standard 24pin and also a secondary four pin block.
seems to me your using an older psu that only carries the 20/24pin power lead. You'll need the psu that also has the four pin block connector. without it the mb will not power up.
Also advice re-checking your case/mb wiring config especially usb connections.

However I would say that it seems like you have missed the four block. Easy done if your not used to the newer mb's.

Daemonic

Fixed
Looks like the 20 pin to 24 pin adapter was dodgy. Bought a new one in peats yesterday and am currently posting this from my ridiculously fast new PC.
Thanks for all the tips and suggestions.