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New build was working fine / shut down / wont turn on

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February 24, 2011 11:02:53 AM

Hello everyone,

I am in a panicking state atm. My newly built pc was working fine but suddely it shut off and now it does not turn on. THere is a green light on the motherboard as always and when I press the power on button I can see a slight movement on the cpu and graphics coolers.

my setup is:
i7 950
asus x5 sabertooth mobo
8gb geil ram
msi gtx 470 frozr
xfx 750w pro core edition.

I have tried reseating everything: gpu, cpu, ram (also tried each stick individually), disconnected all hdd.
Is my psu dead?
please help.
February 24, 2011 4:20:21 PM

update: I tried the mobo, psu, gpu alone outside the case, but same problem. The light on the mobo is on, the fans move 1 cm but nothing happens then. I also tried to switch it on using a screw driver (by shorting the power switch pins); same problem

help please!
February 24, 2011 4:52:52 PM

Work systematically through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
Related resources
February 24, 2011 5:39:44 PM

thank you ever so much!

Ive tried breadboarding and generally most of the things youve mentioned. I just now tested my psu with the paper clip method and having a fan on and the psu is working no problem. Then, I moved to the second step; plugged the power to the mobo having only 1 ram stick on it and the processor+cooler. Same problem. Green led and nothing else is happening, but a slight movement of the processor cooler fan. No beeps

I would like to reiterate that my pc has been built properly, according to the guide you have posted and after lots of research; it was working fine and cool this morning. Suddenly shut off and then it would not power on again.

So my question is: is it possible that the cpu has suddenly burned out? or is it just the motherboard? By the way this motherboard had another issue: the onboard audio was dead since day 1, but I solved it by adding my old SB audigy 1 sound card.

Am I missing something? any further suggestions?

thanks again brother


February 25, 2011 6:10:03 AM

I think I can find another PSU to try with the mobo/cpu/1 ram stick. In that case, if it does not power up/beep, will it mean that the motherboard died? or, is it possible that the cpu/ram might have gone bad too?
February 25, 2011 4:29:49 PM

finally tested out the psu at my local pc repair shop and it is absolutelly fine. The owner was kind enough to test my psu with a voltage tester. Mobo is dead! The technician thinks so too.
!