They probably entered the order without realizing when they pulled the part that it requires a different system, thus our suggestion to totally explain everything. We apologize as its not a different part number, though a different product assembly. Please contact them and they may have to have a custom build done. There were a limited number of bad PCs and the style is the difference. They may have to communicate with techs in production to resolve this for you also. They should have resolved it with the part, thus we also feel they may have to dig deeper and be sure you received the right part. It is also possible they had a defective part remaining on shelf and did not realize it. BCB