Help Needed - Sudden Restarts before and after POSTing

[evanviera]

Hi!

I recently purchased the parts below to assemble a "Hackintosh". With some minor obstacles early on, I was able to install OS X ML. The computer was up and running for about an hour before I experienced the first crash. Without a Kernel Panic or any noticeable freezing the machine rebooted, as if the power cut out and was immediately returned.

This is a reoccurring problem that I can easily tease out using a stress test. Sometimes when the system reboots, it will make it all the way to the OS, other times not so lucky. It will some times restart again before even POSTing AND as of lately it often falls into a reboot loop (Restarts about 5 times before successfully POSTing).

To troubleshoot I removed everything but the RAM, Motherboard, and CPU. With all four sticks of RAM in, I was able to recreate the problem almost immediately. However, with only one or two sticks in, I am able to run 15min stress tests without any shutdown. I don't believe any of the RAM is bad, since I ran 5-10 min Mem Tests on each stick multiple times without any errors. I believe the problem is something more complicated that's a bit above me.

Any thoughts / things to check out?

Thanks in advance.
Evan


- - - -


** Mountain Lion 10.8.2 **
Intel Core i7 3770 3.4 GHz CPU
** BIOS F9 ** Gigabyte GA-Z77-DS3H Motherboard
MSI NVIDIA GeForce GTX 560 Ti (448 Cores)
16GB Corsair DDR3 1600 MHz RAM, 4x4GB
OCZ Vertex 4 512GB Solid State Drive
2TB Western Digital Caviar Black 7200 RPM Hard Drive
Asus 24x DVD-RW Serial ATA Internal Drive
SYBA FireWire 400/800 Card
Corsair Professional Series 650W Modular Power Supply
TP-Link PCI Express Wifi Adapter TL-WDN4800

 

[evanviera]

Here's a little more information. I just ran a CPU stress test for 20 mins with all four sticks of RAM in, and had no crash. Generally the crashes happen before the 10 min mark. I monitored the CPU temp while running the test and no core exceeded 62 C. Therefore, the CPU, sink, and CPU fan, are all working healthily, right?

After the successful test I ran a RAM stress test and bam it crashed within minutes. I was also monitoring the CPU temps, which stayed in the healthy range. So it's gotta be the RAM, right? Or can the Motherboard still be at fault?

 

[evanviera]

I conducted a few more tests...

With all four RAM sticks in the RAM Stress Test causes a restart, as mentioned in first post. With three in, it passes the test fine. Thinking that one of the sticks might be bad, I swapped them around and there was no apparent difference, it didn't matter what sticks were in, just that there were no more than three.

I also thought the fourth RAM slot on the Motherboard might be bad, since I always filled them up in order (slots 1-3, for 3 sticks). So I moved the third stick to the fourth slot (1,2,4 - for 3 sticks), and ran the test again. It passed.

So I can conclude non of the sticks are bad, and all four slots are working. But my machine can't run stably with all four in. What could this be? A BIOS setting, a motherboard fault, and power issue? Man, I'm running out of ideas!