By default, CPU-Upgrade.com starts with the vendor's (Intel's) compatibility list for the chipset. B75, at least officially, doesn't support Xeons. In fact, none of the "Consumer" Ivy Bridge Chips support Xeon.Then why aren't they on the list I linked to above?
Users can load up "this worked for me" configurations to CPU-Upgrade, but I guess nobody has for B75.
Some vendors list Xeon compatibility even though its not official for B75 (or Q77, or etc.). Asrock tends to include a disclaimer like "Because we are awesome we included Xeon compatibility, but because its not native to (insert chipset here), we can't support you if you have issues."
Interestingly, Intel lists Xeon for many of its boards that have chipsets that officially don't support them. My DQ77KB is that way.
So, a Xeon could very well work on this. But, without using a E3-12x5 CPU (the ones with integrated graphics) a GPU will need to be inserted in the PCIe slot, and even then it may not work.