Building a PC with ASUS KFSN4-DRE server/workstation board

It's supported by Libreboot (well, sort of, http://libreboot.org/docs/hcl/kfsn4-dre.html ) and I'm looking to build a desktop, so....

If I use this, what would be the technical drawbacks in doing so instead of, say, using another board and an i7-5775C (apart from the lack of access to a pre-Skylake Intel iGPU)?

Would electric consumption go up (and if so, by how much), for example?

Or would it actually be slower than an i7-5775C (which I'm pretty sure it isn't, nor is it against the Skylake CPUs which numbers I can't remember, but you never know...)?

Will I need a huge casing?