amd's 9xx chipsets support am3+ cpus and both cfx and sli.
do any of these motherboards fit your preference?
ASRock 970 EXTREME4 ATX $140
GIGABYTE GA-990XA-UD3 ATX AMD Motherboard AM3+ CPU,8+2 Phase VRM,2 Way SLI $150
ASUS M5A99X EVO ATX AMD Motherboard with UEFI BIOS AM3+ Ready w/ UEFI BIOS, DIP2, SLI/CrossfireX $150
all have $12.24 shipping. http://www.newegg.ca/Product/Productcompare.aspx?Submit...|13-157-262^13-157-262-TS%2C13-131-754^13-131-754-TS%2C13-128-510^13-128-510-TS
as for performance boost...the cpu, gfx card and ram take priority over motherboard. however, it's the motherboard that allows the cpu to be overclocked more of less that other motherboards.