Modern Intel CPU's integrate a lot of the functionality that used to be
provided by the motherboard chipset. This includes the primary PCIe link.
Socket 1155 CPU's provide a sixteen lane ("x16") link. On some ( generally cheaper) Z77
motherboards, all sixteen lanes are connected to a single x16 slot. Which means:
If you're NOT using the CPU's integrated graphics, then you're devoting the
entire primary peripheral interface of your system to something (ie, graphics) that in the
context of a DAW simply isn't very important.
. . . and if you ARE using the
CPU graphics, then you're presenting your primary peripheral interface in a manner (ie,
one big pipe) where it's almost certain to be under-utilized, since even at Gen 2 speeds,
a x16 PCIe link is capable of 8GB/s full-duplex (and your CPU, having a Gen 3 interface,
is capable of almost double that, given compliant devices).
the primary PCIe link can be split/switched, allowing it to operate as two x8 connections
(OR one x16 if desired, though obviously in this case the second slot becomes redundant).
Both connections will be presented as x16 slots (ie, they will both physically accommodate
ANY PCIe card).
At Scan prices at time of writing, the motherboard you list
in your OP is £83.72, while the "bifurcated" P8Z77-V LK is £102.92.