It would be a better idea to grab something like: http://www.amazon.com/IBM-Serveraid-M1015-Controller-46M0831/dp/B0034DMSO6/ref=pd_sim_sbs_147_1?ie=UTF8&dpID=21jD0PFfhNL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=0GK614Y1459NK25XENRF
That would allow you to add 8 additiona drives (using SAS to SATA breakout cables) and wouldn't run into the same bandwidth issues that PCIE 1X slot would have.