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Computer will no longer turn on!

Last response: in Overclocking
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September 26, 2010 10:30:30 PM

So I just got all the parts for my new system the other day and put it together today. Everything fired up just fine, so I installed Win7, AVG, etc.

I saw a post about easy overclocking on MSI mobos via dip switches, so I decided to try it. Downloaded Prime95 and CoreTemp. Ran for about an hour with a max temp of 28C, so I went ahead, shut it down, and switched to a 10% OC.

Started Prime95 and CoreTemp and ~20 minutes in, max temp was 30C. So I walked away for a while, and when I came back, the computer was off! Worse yet, it will not turn back on!

So I guess what I'm asking is: what is the most likely reason? PSU? or did I fry my board? Here are the basics of my system:

Phenom II X6 1055T
MSI 880GMA-E45
Cooler Master Hyper212+
Mushkin Enhanced Silverline 4GB DDR3 1600
Rosewill Green Series RG630-S12 630W 80+ Certified PSU
No Graphics Card

I switched the dip sw back to normal, cycled the psu, cleared the CMOS. When I push the power button, the fans try to move, then stop. If I disconnect the 4 pin CPU power from the mobo, all the fans and the disk drives power up. This is the only thing I've tried, as I don't know what to do next!

More about : computer longer turn

September 27, 2010 12:40:27 PM

Thanks for the link. I will try breadboarding later today.
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a b K Overclocking
September 27, 2010 1:51:25 PM

And also the "Pull everything except the CPU and HSF" step as that may help isolate what component went bad suddenly. Obviously everything was hooked up correctly as it worked for a while.
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a c 197 K Overclocking
September 27, 2010 5:30:31 PM

Work 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.

Extra details. :) 

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

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.

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...

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 or long single beeps indicate a problem with the memory.

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.

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.
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September 29, 2010 8:07:45 PM

Thanks, I finally got done with work early today and will tear into it! Will let you know what I find.
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September 29, 2010 10:16:38 PM

Ok, so I took everything out of the case. Hooked up PSU, mobo, CPU+HSF, and speaker. No beeps. PSU and HSF fans working. But oops! Forgot to plug in the 4 pin CPU power. Retried and, nothing! No fans running.

To eliminate the PSU, I hooked it up to my old system. No problems. However, this is an Athlon XP 2400+, so it does not make use of the 4 pin CPU power cable. This system has run for 8 years on an Antec 300W PSU.

So where do I go next? Get a different Mobo and try it out? Probably the only way to know for sure if it is the board or the CPU that's the problem. I don't really want to wait too long, as I will have to RMA the defective part(s).

Maybe I'll run out to the local BB and pick one up to try (if they even carry that kind of stuff anymore)! LOL
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