A great budget mobo is the MSI P55A-G55.http://www.newegg.com/Product/Product.aspx?Item=N82E16813130292
It'll allow you to run 8x/8x or single 16x. Also if you worry about 8x/8x vs 16x/16x there is no real world difference. The difference between the two is only 1% of real world performance, and its hardly noticeable.
Scaling of 8x/8x vs 16x/16x: http://www.techpowerup.com/reviews/AMD/HD_5870_PCI-Express_Scaling/25.html
Hope that helped. The V8 is a great cooler, either that or the Cooler Master Hyper 212+ is a great cooler, since for the Hyper 212+ you can actually have dual fans on the heatsink, plus its a phenomenal heatsink for the same price as the V8. Though personally i have a v8 i love it.