Second xeon installation turned to suffer

[idata]

Hi everyone! My motherboard is Intel DS5400xs. I have using single Xeon E5420 without any problem on win 7 64 bit till now. I found a cheap and clean E5420 from Ebay last week and bought it. First i tested the new comer cpu by single boot and it was ok. Then i installed both cpus with proper coolers and tried dual cpu boot with win7 ultimate 64 bit but OS didn't start. I made my system turn single cpu again, opened the windows, started the msconfig and set the number of processor 2. Then i tried the dual cpu boot and nothing happened.

I don't know what should i do.

Questions:

My second Xeon E5420's stepping number is different from the older ones. I don't think the cpu stepping number is an issue during multi processor installation but what do you think about this?

If my motherboard bios update will solve my problem?

Is there any win7 64 bit os setting related with this problem?

Any advices are always welcome.

Best wishes.

Murat

[idata]

Hello.

Actually you already found the problem, the processor stepping should be the same to allow the system to work in a dual processor environment. The CPU stepping determines, voltages, structure set, technologies and features and multiple other fixes and specifications. To allow the system to work with 2 processor you may need 2 processor with the same stepping.

Regards