Soon im going to buy either the Z87 G55 or the Z87 G45 Gaming from MSI.
Both boards are identical, except the latter has a different color scheme, is a tad more expensive and has better audio, all which shouldn't matter for mining. No extra accessories except the gaming one has a door hanger, and thats about it.
Has 3x full size and 4x x1 sized PCIE, wihch im thinking of filling with 7 of R9 290s.
And yes you should ue powered risers for x1 sized ones (smallest) but idk about the x16 ones, you might not need to.
Watch out for R290 cards compatibility with different motherboards. I have 2 brand new MB's that will not run the R290 (Sapphire) with setting that generate > 400 kHash. One is Gigabyte Intel based Z87X-OC - the other is an Asrock 970 Extreme 4 AMD based. I tried all R290 (Sapphire x 2, ASUS, MSI, Gigabyte) firmware combo's before I gave up and plugged it into a ASUS X79 based board where each run at 880-900 kHash. And that was even without any risers and only 1 card in different PCI-E slots (yes tried every combo to get that crap working)
So I would recommend getting a full right of return on the board if it wont run. My 7970 Rig runs fine on the above MB's without hardware failures.
here are my Sapphire R290 BFG settings for 880-900 k - "--worksize 256 --lookup-gap 2 -I 20 -g 1 --thread-concurrency 32765 --gpu-engine 1000 --gpu-memclock 1250-1500 --temp-target 83 --auto-fan --gpu-fan 25-100 --gpu-powertune 20 --temp-overheat 95"
Rig runs stable with max temperature of 83 - usually about 81/82. Fan speed around 70-80% average in 24 Deg C room.
