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Mobo Dead on Arrival?

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December 26, 2010 4:19:38 AM

I just built myself a new mid-range computer for christmas and it will absolutely not post, beep (yes my case has a speaker), or display any output from my GPU. What happens is, it will power on as if it's running normally, and continue running that way. Case fans are all on, gpu/cpu/psu fan's all on, the green light on the mobo is on, cd drive works, and the hdd appears to spin up, but never clicks.
I'm using an ASUS P5N-D, GTX 460, E6800 3.3ghz, and 2x2GB 800mhz RAM, Ultra 750w

Some of the troubleshooting I did to no avail:
- Reset the cmos by taking out the battery and moving the jumper as directed
- Made sure both the 24-pin and the 4-pin are connected
- Tried re-seating CPU
- Removed the Motherboard to check for misplaced screws and standoffs
- Tried another monitor
- Tried both DVI ports on the GPU (no onboard video on this mobo)
- Tried an older (but compatible) CPU
- Unplugged everything but the basics
- Removed the RAM then booted, but heard no beeps
- Jumped the PSU's 24-pin to ensure its working fine
- Tried booting with nothing but CPU and HSF, no beeps, nothing

It's as if the computer doesn't see the video card. Over at the ASUS forums they suggested either a faulty CPU or a faulty motherboard, mostly due to a lack of system beeps, but I've ruled out the CPU by trying another. Does anyone have any suggestions before I have to RMA it? I was really hyped up about finally building a new PC and this is a major road block...

More about : mobo dead arrival

a b Ĉ ASUS
a c 156 V Motherboard
December 26, 2010 1:20:35 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.

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 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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