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System won't POST - Mobo?

Last response: in Motherboards
September 4, 2010 1:50:23 AM

I just built a computer for my parents, not an expert, but not a newbie either.

I have an ASUS P6X58D Premium motherboard and 12GB of Corsair 1333 (6 x 2gb) TR3X6G1333C9

After finishing everything up I hit the power button and all the fans started to spin, but my motherboard's DRAM LED turned Red.

According to the manual this means that that either the DIMM is not properly installed, or not compatible. So I first tried reseating all 6 sticks, and got the same error. Nothing appears on the monitor, no signal.

So I tried the MemOK! feature of my motherboard, thinking that maybe my memory isn't compatible. That was unsuccessful as the button didnt do anything, the light didnt blink etc.

Also, the power button / reset button on the front panel didn't work once I started the computer. I had to power off by turning off the switch on the power supply. Also the power/reset on the Mobo itself doesn't work either once the computer is on.

This is my first problem ever with computer hardware and I'm really not sure where to start. Any idea as to whether its bad DIMM, not compatible, bad Mobo...? My parents have been waiting for this computer for a long time, argh, such a setback :( 

Thanks for any help you can give!

More about : system post mobo

Best solution

a c 156 V Motherboard
September 4, 2010 5:47:07 PM

Work through our standard checklist and troubleshooting thread:
I mean work through, not just read over it.

Breadboard - that will help isolate any kind of case problem you might have.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:

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:
At this point, you can sort of check the PSU. Try to borrow a known good PSU. 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.

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.
September 4, 2010 9:21:46 PM

Best answer selected by rtarrazo.