As you can see, by cramming more of the lower end but impressive GTX 750 Ti`s into a single machine you can create a similar performing machine for less money than the AMD alternative, which is contrary to all the advice given about coin mining up to this initial release of Maxwell. In addition, performance of the Maxwell-based machine should only improve as the Maxwell kernel for cudaMiner is developed further, whereas OpenCL performance for AMD mining has likely been as optimized as we will ever see it."
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips