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Black screen and No Post

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December 11, 2011 11:50:58 PM

Hi tom's hardware community.

I have a fairly oldish build which stopped functioning like it should.
When powered on, all fans start spinning buy the monitor acts like the computer is still turned off. I get no post, no sounds, no windows loading etc... just black forever.

The build is
Mobo: Asus P6x580E (LGA1366 socket)
CPU: I forgot, some intel quad core (i think)
GPU: MSI nvidia 460? i think
RAM: 3 x 2GB Gskill DDR3
PSU: 500W Zalman
HD: 1TB --> Win7 installed, no extra partitions

Now i initially though "Ah, graphics card died" but i noticed that the lights on my mouse and keyboard weren't turning on. I confirmed power was running through USB ports by connecting my USB to Phone connector and my phone started charging off it.

I just need some confirmation as to what component is the culprit. I'm 90% sure the graphics card is dead, 8% something went wrong with motherboard (because of no lights on peripherals), 2% cosmic alpha particles struck my computer and everything died simultaneously...

Unfortunately i don't have another platform to test components individually, so my only option is buy a replacement component and hope i chose correctly. I have confirmed that all peripherals work as i plugged them into my laptop.

Thanks.

More about : black screen post

a b B Homebuilt system
December 12, 2011 12:16:02 AM

It is unlikely that it is the graphics card at fault, and much more likely that the power supply is faulty. If you have no spares it would probably be cheaper if you were to take the computer to a repair establishment and ask for a quote.
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December 12, 2011 12:27:03 AM

That power supply is a spare. Its the only spare component i had. the same thing happens with my usual supply (which is also another zalman 500w). I thinks its unlikely that both PSU's are faulty.
I also don't want to take it to a repair establishment because they all take ages. (I live in Australia)
If i can buy a part, i can swap it out immediately.
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December 12, 2011 2:29:26 AM

i managed to get hold of an old evga 780i mobo and confirmed that the problem is NOT the graphics card but probably the motherboard.
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a b B Homebuilt system
December 12, 2011 4:46:34 AM

You have of course tried the obvious things like resetting the CMOS memory and removing and refitting the memory etc?
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Best solution

a c 122 B Homebuilt system
December 12, 2011 4:50:58 AM


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 no luck, 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 (standby power supply): 5 volts always on. The green wire should also have 5 volts on it. It should go to 0 volts when you press the case power button, then back to 5 volts when you release the case power switch. 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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December 22, 2011 2:58:45 AM

Best answer selected by botagar.
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