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Computer does not POST (no beep), No Video, Tried everything!

Last response: in Systems
June 22, 2011 4:05:02 AM

Hi, before I start, here are my computer specs:

Motherboard: GIGABYTE GA-P55-UD3R
CPU: Intel i5-750
RAM: OCZ PC3-12800 Obsidian 4GB Dual Channel Kit
PSU: OCZ 500 Watt
Video Card: GIGABYTE GV-R455D3-512I
OS: Windows 7 64-bit

I built this system about 1.5 years ago and it hasn't had any problems until now.

What happened was about 4 weeks ago I opened up the heatsink and replaced the thermal paste on the CPU with artic silver 5 because I noticed that the CPU was running hot (windows 7 kept on running some networking file whenever idle that caused like 90% CPU consumption and I couldn't turn it off, only not be idle...temps were like 38 C to 66 C intermittently). After replacing the thermal paste, the computer ran well for 3-4 weeks. Then I turned on the computer a couple days ago and while I was browsing on the internet it just rebooted.

After it rebooted, I got a black screen on my monitor and nothing showed up.

Since then, whenever I try to boot, there is no POST, no beeps, and a black screen.

So far, this is what I have tried. I have removed/reseated the RAM, I have tested the PSU with the multimeter, I have built the system outside of the case to check for shorts, I have tried to boot the system with no RAM, no video card, I have taken off the heatsink and re-seated the CPU, and I have reset the CMOS manually. Still, all I get is no POST, no beeps, nothing.

The speaker was working up until the last known good boot a couple days ago so I don't think that the speaker is the problem.

When the computer powers up, the hard drive powers with it, the fans spin, and the lights come on in the motherboard and on the LED in the front.

One thing I did notice is that even though the CPU fan spins, it doesn't seem like it spins fast enough and the heatsink on the CPU never gets hot.

I specifically tested the CPU 8-pin 12 volt power source from the PSU.

I have filed the question with GIGABYTE but haven't received a response yet.

Maybe you guys can help me because I'm really out of ideas and disappointed

a c 103 B Homebuilt system
a c 850 à CPUs
June 22, 2011 12:52:44 PM

Without the luxury of spare parts it is hard to tell but certainly can be the motherboard. Especially if you are getting no beeps with either ram removed or GPU removed.
June 22, 2011 1:07:01 PM

Damn yeah I don't have many spare parts...none are going to work with this motherboard at least since they are from different generations. Maybe I'll just buy something to test it out and then return it.
Related resources
June 22, 2011 1:07:01 PM

Thanks, anybody else have any ideas?
a c 122 B Homebuilt system
a c 172 à CPUs
June 25, 2011 1:47:05 PM

Back to the breadboard ...

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.

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.

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.