socket 1155? if so, you may want to remove the motherboard and look at the back plate, if you google image "socket 1155 ILM" (integrated latching mechanism ) youl see what SHOULD be there, a rectangle, however on my xps 8700 (socket 1150) they used a proprietary ILM which melds the ILM plate with the stock intel back plate (the back plate that looks like an X that covers the motherboard holes) if they did the same thing to the xps 8500 im afraid your out of luck, unless you can find a heatsink that fits those holes exactly. on the 8700 this means a "spring screw" heatsink, i have no hands on experience with an 8500 so not sure what youd need, but i wish you luck, so far the only spring screw types im finding are for 1U and 2U servers.

oh, i should note that if you can find one that has screws, and the threads match, and you can manage to mount it with OUT needing to change out the back plate, it MIGHT work, though i need to state you do so at your own risk. so if your comfortable id remove the motherboard to look at that backplate before buying any thing.

bro, u are using cooler master vortex or vortex plus?