Best Opteron for Tyan K8W (S2885) Motherboard

[Circa 3000]

Hi all,

I'm looking to upgrade my Tyan Thunder K8W from dual Opteron 248s. I presume its running at 3.0 GHz but am not sure. Is it better to go with two single-core 256s (at 1.4 - 3.0 GHz) or two dual-core 285s (at 1.8 - 2.6 GHz)?

If I go with the dual-core 285s, will I need different memory to account for a change to bus speed?

Can I safely do this without having to re-install Windows XP?

Any help is greatly appreciated. Thank you!!!

 

[Circa 3000]

I'm sorry for the duplicate post. I kept getting "flood attempt detected. You cannot post this message." But then, apparently, it posted the message anyways? No doubt, I goofed somewhere. Grrr....