Hi Mustanggt,
I had a post about this very same question recently. Here's a link to the page with the question and answer:
click here.
Obviously, the DS4 is $55 cheaper (newegg). The DQ6 has 2 more SATA slots. It also has a heatsink on the underside of the board. If you plan to install an aftermarket heatsink, you might have to remove it, thus negating its existence in the first place. The DQ6 also features Quad-BIOS. Basically, there are 2 BIOS chips on the board itself. If one has an error, the other works and copies itself to the one with the error. That part of it is known as Dual-BIOS and is featured on the DS4. The Quad-BIOS does that AND also has back-ups involving optical storage devices, USB, HDD, etc.
Physically, the DQ6 has a slightly different heat pipe than the DS4. I don't think those minor differences make it worthwhile to spend an extra $55 or so. I'd rather get the DS4 and put the money I saved towards a decent CPU cooler.