Hmm, well currently it has to be dual Xeon. Ti4600 & new professional cards have issues under Dual Athlon and this is across the board of all makers, performance is very poor indeed. We have not published any Dual Athlon results with 6210 900 & 750XGL. Under dual xeons the boards and applications fly.
A hurried fix is underway at present to 'sort' the chipset drivers however this is going to take 4 - 6 weeks minimum we have been advised.
So maybe that helps you out.