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CPU problem? No POST, CPU LED is lit. i7 2600k, ASUS Maximus IV

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June 4, 2011 12:59:50 PM

Hey all, thanks for helping me out.

I'm probably going to try taking everything out and breadboarding just the CPU/HSF after I post this, as that's all theres really left to do from what I've read on other posts. Anyways here's my problem:

After installing all my parts and getting it into the case, The first turn on yielded no POST or beeps of any kind. Checking the LED's on my mobo, the CPU LED is lit (seems to be the only one that is lit) which, according to the manual, indicates a problem with the CPU. After seeing this, I removed the H70 Cooling system I had installed, and instead installed the stock HSF to see if that might possibly remedy the problem. It didn't.

When I start up, there are no beeps at all. I'll list everything that's in the computer:

ASUS Maximus IV Mobo
Intel i7 2600k CPU
4x4GB Corsair Vengeance RAM
WAS using H70 Corsair cooling system, now using stock HSF that came with the i7
Corsair AX1200 PSU
MSI GTX580 Lightning edition video card
WD Caviar Black 1TB HDD
Intel 510 series 120GB SSD
LG Blu-Ray R/W optical drive
Case is a HAF X

I really hope someone can give me some advice to do some final checking before I RMA the CPU. Thanks.
June 4, 2011 5:33:46 PM

Basically I need to know if it is the CPU or the mobo that needs replacing... and I have no extra CPUs/Mobos to swap out to test :( 
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a c 122 B Homebuilt system
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June 5, 2011 3:22:09 AM

Without further troubleshooting, there no way to know.

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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June 5, 2011 4:27:36 PM

Did most of that, but I have solved the problem, finally found someone nearby with a mobo with an 1155 socket, and the CPU worked in that. Guess I'll be RMA'ing the mobo. Thanks for your help.
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