I am looking at purchasing the ASUS Sabertooth AM3+ 990FX Rev 2.0 GEN3 motherboard. The board has 3x PCIe 3.0 @x16, and 1x PCIe 2.0 @x16. The spec says that the two PCIe 3.0 slots can run in dual x16 mode, or tripple PCIe 3.0 in x16, x8, x8. The single PCIe 2.0 slot also runs in x16. Does this mean that if I were to run three PCIe 2.0 GPUs with 2 gpu cards in the PCIe 3.0, and 1 gpu in the PCIe 2.0 that all three cards would be able to run at full x16 PCIe 2.0 spec?
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Hmmm. I wonder if they listed PCIe 3.0 because they are compatible, which they are. I'd want to read more. From its manual:
"AMD® 990FX Chipset
AMD 990FX Chipset is designed to support up to 5.2GT/s HyperTransport™ 3.0 (HT 3.0)
interface speed and dual PCI Express™ 2.0 x16 graphics. It is optimized with
AMD AM3+ and multi-core CPUs to provide excellent system performance and overclocking capabilities.
PCI Express®3.0 (PCIe 3.0) is the latest PCI Express bus standard with improved encoding
schemes that provide twice the performance of current PCIe 2.0. Total bandwidth for a x16
link reaches a maximum of 32GB/s, double the 16GB/s of PCIe 2.0 (in x16 mode). As such,
PCIe 3.0 provides users unprecedented data speeds, combined with the convenience and
seamless transition offered by complete backward compatibility with PCIe 1.0 and PCIe
2.0 devices. PCIe 3.0 will become a must-have feature for users who wish to improve and
optimize graphic performance, as well as have the latest technology available to them."
This is unclear; I'd like to see it tested. The chipset supports PCIe 2.0, so where are they getting 3.0? Not that it's a big deal; current cards do not max PCIe 2.0 slots.