Z800 Dual CPU Upgrade

[Doberman4]

I upgraded my HP Z800 Workstation (FF825AV) with matching CPU Xenon X5670, replaced 18 GB memory, (6 x 3GB) with 48GB, (12 x 4 GB), each CPU 24 GB. Have upgraded BIOS per HP installation instruction and I have BIOS version v03.61, the Boot Block Date is 11/10/09. After installation, the computer failed to boot no beep sound, but a few second after starting the fans go full bore other than that I get blank screen.

I have tried each CPU separately and work fine as a single CPU but when both are installed it don't boot.

I will thank any help that I can get.

[DGroves]

there is a small white sticker on the motherboard near the cmos reset button/large black heatsink  does it say  AS#xxxxxxx-003

[Doberman4]

Yes, it does have that number. What do I do to make it work?

Thank you

[DGroves]

are these retail or ES/QL sample cpu's

if each cpu works in socket 0 and neither works in socket 1 and if RETAIL cpu's then you most likely have a bad motherboard

the only other test you can try is to get 2 of the cheapest 56 series cpu's and try them to see if it is indeed the motherboard

[Doberman4]

Yes they were retail CPUs, thank you so much for taking your time to help; greatly appreciate it, I had a hunch something must be wrong with the motherboard since it did not work when I split the 6 sticks of 3 GB memory providing 9 GB for each CPU. I wasted $80 buying 48 GB memory assuming it  would work on even rather odd mem configuration. I will think about getting another motherboard, the additional CPU fan (new), the matching processors and memory cost me $300, I would have been better off to buy used one for some $500.

[DGroves]

the z800 unlike other systems uses TRIPLE channel memory and is populated in groups of three (not 2 or 4)

please look at the memory load order found on the side cover or at the link below

http://h20331.www2.hp.com/Hpsub/downloads/Mini_WP_Z800_memory.pdf