Physically the x4 slot is open ended.  Whether it can run a x16 card?  not certain how much power the x4 slot can supply to the card. some one said this to “Can I put a 16x graphics card in a 4x slot and it still work?” “Yes. It will work fine. It won’t run quite as fast as it will in a 16x slot, but the performance penalty isn’t 75 percent (4/16), it’s usually in the range of 5 to 10 percent. Modern graphics cards don’t come close to saturating an x16 PCIe lane, and rarely come close to maxing out x8 even under the maximal load scenario.” [IMAGE]  
Is the x4 slot on the XPS 8930 motherboard open ended, meaning a x16 graphics card can be installed in this x4 slot (and run as x4 of course)?
XPS 8930, is the x4 slot open ended?