Build won't boot after installing 2nd CPU

Hey all hoping I can get some tips or thoughts on what to try next. I’m new here but have been lurking for a while and somewhat new to server building but not new to PC building as I’ve been doing it for the past 20 years.

Quick rundown of my hardware:

Purchased a SuperMicro X8DTL-IF Motherboard with existing Dual E5504 processors off eBay. Tested and working fine.
Existing R410 Dell 1U with Dual X5650 and 32GB of Ram (8 sticks) tested and working fine. Going to use this SM & the Dual X5650s into a spare ATX case that I have as well as a Thermaltake TR2-500 and using an EPS splitter for the dual CPUs.

So I installed the X8DTL-IF into a case, and test booted with the exisiting Dual E5504s and 24GB of Ram (since this board only has 6 slots). Boots no problem.

After some installing/troubleshooting with both X5650’s and not getting any boot screen, I decided to try just one E5504, and it booted no problem. Next thought was to upgrade BIOS so I upgraded the SM Bios to 2.1 which is the latest on SuperMicro’s website.

Installed just one X5650 and it booted no problem. Once I install the 2nd X5650, the server no longer boots. CPU fans spin but nothing every comes on the screen. No beeps, no codes to go by.

Anyone have any ideas? I do have another Power Supply - Cooler Master RS-600-PCAR-E3 to try if you all think it could be power related, but the X5650s don’t use THAT much power, so I don’t think that could be it.


Does the other X5650 work on its own in the first slot? I.e., isolate if the CPU itself might be faulty. Also, I’d run any tests with just one DIMM per CPU. Also best to test outside of case.

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Thanks for the suggestion. I have not tried CPU 2 in the 1st slot by itself. Will try that tomorrow and report back.

And agreed on the 1 DIMM, I just left them in since it was working in all of the other configurations.

@seanho not sure what it was, but put CPU 2 into the first slot only and it booted. Then put CPU 1 in the 2nd slot and it booted. I hooked an OS drive up and been monitoring temperatures and everything looks great.

Unsure what I fixed but it’s working now.

Glad to hear you got it sorted! Heh, now just don’t touch the CPUs again, for fear it may die again!

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X5650 only in slot1, board starts but debian11 (truenas7) is not booting…

Dual X5650 SYSTEM - BOARD NEVER STARTS, however 2nd CPU works okay in 1 slot.
E2609 - single Cpu TrueNas boots fine.