[CentOS] Tyan K8SRE troubles with CentOS 4.4 i386

> configurations. The x86_64 vs. i386 difference is odd; maybe they treat 
> the memory controllers differently?

Maybe lack of AMD IOMMU support in the i386/i686 kernel?

> 
> Where would I find official warnings about memory-size mixing? We can 
> bring it up with the vendor. The motherboard manual doesn't have such 
> caveats. Is this oral tradition?

I had problems POSTing on a Tyan 2881 with two 242 Opterons using RAM 
from the same vendor (4 sticks of 512MB) because two of them were a 
different batch. After getting those replaced with verified modules did 
I get my 2GB worth of RAM.