ASUS P5K64 WS Motherboard Review
 

ASUS offers no fewer than 12 motherboards based around Intel's P35 chipset. We've already reviewed two, the P5K Deluxe and P5K3 Deluxe, and now we're checking out the P5K64 WS workstation board. This has four PEG slots but not enough lanes for four graphics cards to all run at full width.

http://www.hexus.net/content/item.php?item=9474