X58A-UD3R v2.0 won't power up, NB PHASE LEDs on

[aerikg]

So here's the story:
 
I removed a Gigabyte X58a-UD3R v2.0, i7-940, and 6x1GB corsair platinum ddr3 1333 from my main home office machine and placed it in a "nMEDIAPC Red Wood Wood/Steel HTPC 8000" case (my living room HTPC). This replaced a phenom matx setup in the same case. With this, I installed a new CPU cooler (Enermax ETD-T60),a noctua 140mm exhaust fan,a generic RADEON 6450, and a pci-e x1 wireless-n adapter. I used a 60GB force 3 SSD for the OS on AHCI and 2x1.5TB WD green on a RAID 0 for storage.
 
I may have gone wrong here: I repalced the 450w earthwatts PSU with an OCZ ModXStream Pro 500W Modular PSU. I tested the power consumption previously (in a different case) with the 6450 and different (still 3 in total) hard disks and it idled at 178 watts, and pulled 454 watts under load.
 
After assembly, I installed W7 and everything went fine. Machine was responsive and stable. A couple of hours after I had deemed this effort a success, I started copying 2TB files off of my home server to the RAID array over the (wired) LAN. It was late at night and Windows said this would take 6 hours, so I went to bed figuring it would be done in the morning. The next morning, BOTH computers were powered off as if there was a power outage. I fired the server back up without issue. The Gigabyte/i7 HTPC did nothing when I pressed the power button.
 
With the PSU on, after hitting the power button, the fans spin for a millisecond, the CLEAR CMOS button on the i/o panel stays illuminated, and 3 of the NB_PHASE LEDs stay lit; 1 green and 2 yellow. Attempting to decipher the exact meaning of these lights has been an exercise in futility. The machine acts as if there is a short on the board. The mb/cpu/ram setup ran stable at stock speed for 14 months prior.
 
In diagnosis, I removed the battery, removed the entire setup from case and tested on bench, tried several different DIMM configurations, tried another PSU, tested with everything disconnected, tried an alternate cpu cooler, all to no avail.
 
I have built dozens of machines in the past, and these problems drive me crazy. I thought I would seek advice here before throwing more money at it.
 
Thank you for your advice in advance.

[MiiCK]

Some things to try:

Remove all non-necessary items from the motherboard, ie gfx card, hdd, dvd drive, noctua side fans etc and see if you can boot to the bios.
Try more ram and only 1 stick in slot #1 per time, run memtest86+ on the ram you have to double check it.
You say you removed the battery, for how long? These boards hold power for quite a while, i'd suggest leaving it out for an extended period of time.
Have you checked all connections are secure? ie the 8pin connector plugged in the board and 24pin cable to the board too?
Are you running it on a cardboard box now, not back in the case?
Can you put the hard drive in another machine and boot into it fine?
Can you remove the heatsink and fan, the cpu too, and check there's no bent pins on the cpu socket...?
If the cpu socket is fine (take pics close up so we can see it, to give you a second opinion), then replace the thermal paste (totally remove the old paste) with a tiny pea size dot of thermal paste in the center of the cpu, no need to spread it out as the heatsink will do it. then connect the heatsink to the motherboard and make sure it's correctly seated in position.
It seems weird how both pc's would be turned off by morning, can you rule out a power cut? (ie times changed on home phone, dvd player).

Try some of the ideas posted above and come back to us 

[teknology9]

Hi,

With regards to your PSU..the recomended minimum is 650w. Not wanting to state the obvious a good PSU is at the heart of every system....but sometimes this fact is overlooked.

Have a read of this......

http://blog.corsair.com/?p=4257

Teknology9