Quote from: 23940103 on January 11, 2014, 09:29:19 PM

what am i missing?

GIGABYTE GA-990FXA-UD3 AM3+ AMD 990FX SATA 6Gb/s USB 3.0 ATX AMD Motherboard
AMD Sempron 145 Processor
(2) Corsair RM Series 850 Watt ATX/EPS 80PLUS Gold-Certified Power Supply - CP-9020056-NA RM850
P3 International P4400 Kill A Watt Electricity Usage Monitor
Kingston Technology HyperX 8 GB (2x4 GB Modules) 1600 MHz DDR3 Dual Channel Kit (PC3 12800) 240-Pin SDRAM KHX1600C9D3K2/8GX

using crates

(2) Powercolor Radeon R9 280X OC 1030MHZ 3GB 6.0GBPS GDDR5 DVI HDMI 2XMINIDP PCI-E Video Card
(1) Asus MATRIX-R9280X-P-3GD5 Radeon R9 280X DDR5 3GB256-bit PCIE 3.0 DVI/DP/HDMI
(1) GIGABYTE Radeon R9 280x OC GV-R928XOC-3GD REV2
(1) XFX R9-280X-TDBD AMD Radeon R9 280X 3GB GDDR5 2DVI/HDMI/2Mini DisplayPort PCI-Express Video Card

I'm confused on the risers
Expansion Slots: 2 x PCI Express x16 slot running at x16 ,1x PCI Express x4 slots, 2 x PCI Express x1 slot, 1x PCI slots

do i need (5) 16x1 risers or
(2) 16x16, (1) 16x4, and (2) 16x1

Im planning on running ubuntu on a memory stick since i read that's the best way to go!

You could do it with either (2) 16x16, (1) 16x4, and (2) 16x1 powered risers or (1) 16x16 and (4) 16x1 powered risers. Most OS drivers get a bit uppity if the primary video card is not x16.