AMD 64 motherboard recommendation

[mark at buttery.org (Mark J. Dulcey)]

Christoph Doerbeck a242369 wrote:
> One of my biggest complaints of AMD based motherboards of late is the
> lack of support for ECC memory.  If I'm putting >2GB in a box, I'd prefer
> to spend a little overhead for a big peace of mind.
> 
> Which AMD64 are you considering?  If I understand it, the high end version
> (opteron?) has the integrated memory controller, where as the lower end
> consumer version does not?

All AMD64 series processors have the memory controller on-chip. The 
difference is that the Opteron has a 128-bit-wide interface (2 DIMMs 
simultaneously), but the Athlon 64 only has a 64-bit-wide interface. The 
Opteron requires registered DDR SDRAM (more expensive and higher 
latency, but it allows higher capacity); the Athlon 64 can use 
unbuffered DDR SDRAM. Both memory controllers support ECC. It's a 
mystery to me why there are Athlon motherboards without ECC support, 
since you get it for free with the AMD64 architecture. By the way, the 
Opteron also has ECC for its on-chip cache memory.

But as things stand, you pretty much have to go with an Opteron rather 
than an Athlon 64 to get a system with ECC support; for whatever reason, 
the readily available Athlon 64 mobos don't seem to include it. The 
catches: more expensive CPU and motherboard, more expensive registered 
RAM, higher memory latency can hurt gaming performance. The good stuff: 
multiprocessor support is available (the multiprocessor-capable Opteron 
CPUs cost more than the ones without MP support, though the 2xx series 
for dual-processor systems isn't too bad), higher total memory bandwidth 
(if you install DIMMs in pairs) means higher performance in server 
applications.