I actually have a fully functioning C2750D4I that is a later version with a C0 stepping CPU. The C0 stepping CPU has a different heatsink design which screws in from the bottom with springs for tension. There are no standoffs on the CPU heatsink. This is probably the biggest giveaway between the two CPUs and this is why I am thinking this is a heat related failure.
I have verified that the memory I am using works fine in my working system. I have also "hot swapped" the BIOS to flash the bad board BIOS with the latest BIOS. The IPMI/BMC BIOS is up to date since you can flash that from IPMI.
The CPU is definitely generating more heat in the heatsink since I replaced the thermal pad - but even a dead CPU will generate heat.
I do not have a device to read post codes - I have just about everything else . . . LOL I need to get one. However, when looking at the PCB, the components for the audio output seem to be populated, there is just no header. I will take another closer look and if everything is there, I might just solder in a header and plug in a speaker to see if it sends out post code beeps.
To buy a post code reader, should I buy a TPMS version or PCIe version?
What would you recommend I should take as my next steps?
BTW, I am seriously contemplating purchasing a C0 stepping CPU and swapping out the CPU. I do a lot of SMT assembly with QFPs, just never attempted a BGA. I found the correct BGA stencil (and holder) to use with the C2000 series CPU and even found a C0 C2750... shouldn't be too hard. In regards to SMT, I have been using SA305T4 paste and have been extremely happy with it. Have had no issues with QFP 100 packages and even tolerates poor stencil quality with no solder balls. So this probably would be ok for the BGA. The biggest challenge will be proper final reflow peak temperature without harming the plastic components... not undoable, but don't think I will be able to utilize my reflow oven for final peak temperature. I will probably have to result in using my hot air workstation.
Loctite GC 10 SA305T4 Data Sheet
Some other notes: The power switch turns "on" the mobo. A long hold on the power switch turns "off" the mobo. I have no way of knowing if the reset button works. Haven't checked the state of the system fans. Normally, the fans come on high, then throttle back during POST. I will check that when I check the audio output.