Bios cannot detect second CPU

[hextane]

Hi, I hope you guys can help.

Setup:
Asus Z9PE-D8 WS
2x Xeon E5-2665 (qa8e spec)
2x Kingston 16GB PC3L-10600R Server memory modules (KTH-PL313LV/16G)
Seasonic Platinum 660w PSU
EVGA Geforce GTX260
Windows 7 Professional x64

The CPUs show up in the Bios and CPU-Z as "Genuine Intel (Sandy Bridge-EP) (ES)", and both have 8 cores/16 threads each.

Both CPUs work individually in CPU socket 1. When tried individually in socket 2 the system does not power up at all (however I'm pretty sure socket 1 has to be used for a single CPU setup). When both CPUs are put back together the system powers on for 3-4 seconds, shuts down and repeats indefinitely, until I do a CMOS reset and it boots into windows first time no problem, however in both OS and Bios it still only shows one CPU installed.

I've tried CMOS resets, switching the video card to an old 8800GS, swapping the RAM with two sticks of 2gb Kingston HyperX Genesis 1600mhz, swapping around the two 8-pin CPU connectors from the PSU, and I have checked with the MoBo Manual that the ram sticks are in the correct positions.

Any ideas as to what could be causing this?

Thanks

 

[popatim]

Do you have ram in the slots for the 2nd processor?

 

[bmacsys]

Hi, I hope you guys can help.

Setup:
Asus Z9PE-D8 WS
2x Xeon E5-2665 (qa8e spec)
2x Kingston 16GB PC3L-10600R Server memory modules (KTH-PL313LV/16G)
Seasonic Platinum 660w PSU
EVGA Geforce GTX260
Windows 7 Professional x64

The CPUs show up in the Bios and CPU-Z as "Genuine Intel (Sandy Bridge-EP) (ES)", and both have 8 cores/16 threads each.

Both CPUs work individually in CPU socket 1. When tried individually in socket 2 the system does not power up at all (however I'm pretty sure socket 1 has to be used for a single CPU setup). When both CPUs are put back together the system powers on for 3-4 seconds, shuts down and repeats indefinitely, until I do a CMOS reset and it boots into windows first time no problem, however in both OS and Bios it still only shows one CPU installed.

I've tried CMOS resets, switching the video card to an old 8800GS, swapping the RAM with two sticks of 2gb Kingston HyperX Genesis 1600mhz, swapping around the two 8-pin CPU connectors from the PSU, and I have checked with the MoBo Manual that the ram sticks are in the correct positions.

Any ideas as to what could be causing this?

Thanks

OK, do you have two voltage regulators? Many server boards ship stock with only the single one. I know Seasonic is top notch but is that enough of a psu? That is a serious effing mobo!

 

[bmacsys]

Do you have ram in the slots for the 2nd processor?

I don't think how you populate the ram dimms has anything to do with this type of problem.

 

[popatim]

For a single cpu install, The two dimms would be in A1 & B1. For a two cpus install those same two dimms need to be in A1 & E1.

 

[bmacsys]

For a single cpu install, The two dimms would be in A1 & B1. For a two cpus install those same two dimms need to be in A1 & E1.

I am sure he has that covered.

 

[hextane]

Hi, I hope you guys can help.

Setup:
Asus Z9PE-D8 WS
2x Xeon E5-2665 (qa8e spec)
2x Kingston 16GB PC3L-10600R Server memory modules (KTH-PL313LV/16G)
Seasonic Platinum 660w PSU
EVGA Geforce GTX260
Windows 7 Professional x64

The CPUs show up in the Bios and CPU-Z as "Genuine Intel (Sandy Bridge-EP) (ES)", and both have 8 cores/16 threads each.

Both CPUs work individually in CPU socket 1. When tried individually in socket 2 the system does not power up at all (however I'm pretty sure socket 1 has to be used for a single CPU setup). When both CPUs are put back together the system powers on for 3-4 seconds, shuts down and repeats indefinitely, until I do a CMOS reset and it boots into windows first time no problem, however in both OS and Bios it still only shows one CPU installed.

I've tried CMOS resets, switching the video card to an old 8800GS, swapping the RAM with two sticks of 2gb Kingston HyperX Genesis 1600mhz, swapping around the two 8-pin CPU connectors from the PSU, and I have checked with the MoBo Manual that the ram sticks are in the correct positions.

Any ideas as to what could be causing this?

Thanks

OK, do you have two voltage regulators? Many server boards ship stock with only the single one. I know Seasonic is top notch but is that enough of a psu? That is a serious effing mobo!

There's one VRM for each CPU. When running on one CPU CoreTemp has only read a maximum of 70w being drawn during a Prime95 stress test, and the PSU quotes a maximum combined load of 660w for 12v outputs.

The "power on > cut off > repeat" cycle that happens when using two CPUs is exactly the same as when I tried to boot with only one 8pin CPU connector, which points to a fauly PSU perhaps? The 8pin connectors work fine individually though.