According to this post on the Dell forum (http://en.community.dell.com/support-forums/desktop/f/3514/t/19492096), while the Intel H67 chipset does technically support Ivy Bridge CPUs, the Dell XPS 8300 series does not support Ivy Bridge. The newest i7 you can use in it is probably the i7 2600. You could get a 2700k and even if you did get a K CPU, it would kind of be a waste since you would need a Z-series motherboard to be able to overclock it. Return the 3770k and get a 2600 OR keep the 3770k and get a cheap H77 or Z77 motherboard that fits your chassis. I got an Asus P8H77-M LE a few months ago for $60. A brand new Z77 can be had for under $100. That would be the best upgrade you could do for that PC. Even an non-Dell H67 should work with the 3770k assuming its BIOS is up to date, but since you already have a 3770k, you might as well get a Z-series board to pair with it and take advantage of all the features the k-series chips have to offer.