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Problem: comp wont start

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March 20, 2011 10:34:42 AM

Hi everyone

I am here to ask the pro and simi pros for some advice. I have a homebuilt system that all of a sudden died on me. I turned off my computer one day and when I tried to turn it on a few days later it wont start.

Symptoms: I can hear an electrical howling noise very high pitched, very faint nothing unusual here. Basically the electrical hum of my system. (very similar to the sound of a tv). No fans spin up, my hard drive doesn't spin up. I have experienced something similar to this when the two fans on my tower where turned off. except then the system blinks on and then dies. (build in safety feature I guess) It behaves the same except that it doesn't power up at all. You could compare it to the power button not responding at all.)

system completely dead and non-responsive.

I can see my mother board lighting up. and have tried to turn it on using the onboard power button. But nothing happens. I am at a loss here as to what it could be, and any ideas on what I should try would be very appreciated.

Here's to hoping you guys can point me in the right direction

System specs. (in case they are useful):
Asus striker extreme main board
intel quad core CPU
4 blocks of corsair mem
2 x GeForce 8800 GT SLI config
SSD bootdrive
1 SATA harddrive
Note watercooled system. (no leaks or moisture I can spot) And my system does seem to be very dusty inside.
March 20, 2011 12:01:55 PM

If you take the side panel off your case, do you see the GREEN power LED on the motherboard? Is it lit?

I looked on NewEgg, this seems to be your MB:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

unfortunately it won't let me zoom in on the pictures of the board, is there a diagnostic display on your board? (any codes...)


Let's get back to the GREEN power LED. It should be ON if your system is plugged into the wall & the power switch on the back of your power supply is On. Doesn't matter if the system is off.

Do you see ANY activity on any LEDs or diagnostic displays when you press the power button to turn on the system?

If you see Nothing it's likely your power supply has died. OR, is so overloaded it can't boot the system. This is True : Since power supplies age, they weaken and loose power.

What brand and model of power supply do you have?
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March 20, 2011 2:51:25 PM

Wow, a 520watt supply on two (2) 8800's. It's certainly put up the good fight keeping the system working at all....but as PS age they get weaker...

You could try to remove both GPUs and see if the system will power up (hey, doesn't have to work just want to see if things will start up will FAR less load on the PS...)

Then, if it powers up, try just ONE GPU, just need to get the system to boot to BIOS or OS to see if it's still alive...

If it's alive its power supply time...

Too many people under estimate the importance of a strong, quality power supply. Choose one from Corsair, Antec TP, or Seasonic...
650watts will work for any single GPU system.
850Watts will work for all but the highest end dual GPU systems.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...


The 650watt should get your board started but the 850watt will be more future proof (& with a 7 year warranty it will out last your next 2 or 3 builds...)


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a c 122 B Homebuilt system
March 20, 2011 5:21:27 PM

If you pull one video card and your system starts, you have found the problem - inadequate power. If it still doesn't start, you have more work to do.

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.
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

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.
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March 22, 2011 5:58:38 PM

well tried pretty much every thing.. I'm down to the conclusion that either I have a dead PSU, mobo or CPU on my hands.. here's hoping for the mobo, since I have a spare lying around.

Wierd thing about the PSU is that it had been running without a prob for 2+ years. Weird thing about the other stuff. Haven't fooled around with it, so I don't see why it should have died so suddenly and while turned off. Some thing doesn't quite ring true to my ears, can't poot my fingire on it, but something strange is going on :) 

tried without soundcard, gfx card, one ram block and no water cooling still totaly dead. except for a few led's on the mobo. (power, reset and republic of gamers logo)

but anyhow thx for all of your help, I think I'll try to get my hands on a PSU if that fails I gues I'll try the other mobo before buying a new one. Just gotta suck changing that, emptying the water and ***..

but thx guy's :) 
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