PCI Express Lane Configuration

supermicro

I'm trying to figure out the correct motherboard to buy for a PCI-E card I have. I have decided on the board here,

http://www.supermicro.com/products/motherboard/Xeon/C600/X9DRW-iF.cfm

However I cannot figure out if the PCI Express x8 slots are powered sufficiently when looking at the below text from the manual for the network card. The portion that worries me is "This is because some slots (including
those that are physically x8 or x16 lanes) may only electrically support x4 lanes." does anyone know if this motherboard will be powered correctly for the full speed of the card? On a side note I do plan to utilize both CPU sockets as I know that will affect the powering of the PCI-E.

The PCI Express (PCIe) interface used to connect the adapter to the server can function at different
speeds and widths. This is independent of the physical slot size used to connect the adapter. The
possible widths are multiples x1, x2, x4, x8 and x16 lanes of (2.5Gbps for PCIe Gen 1, 5.0 Gbps for
PCIe Gen 2) in each direction. Solarflare adapters are designed for x8 lane operation.
On some server motherboards, choice of PCIe slot is important. This is because some slots (including
those that are physically x8 or x16 lanes) may only electrically support x4 lanes. In x4 lane slots,
Solarflare PCIe adapters will continue to operate, but not at full speed. The Solarflare driver will
insert a warning in the Windows Event Log if it detects that the adapter is plugged into a PCIe slot
which electrically has fewer than x8 lanes.

Best Answer

does anyone know if this motherboard will be powered correctly for the full speed of the card?

Depends on the riser card you use. Not dependent on the motherboard itself.

On a side note I do plan to utilize both CPU sockets as I know that will affect the powering of the PCI-E.

Only to the extent of which riser card slot is connected. Socket 00 (CPU1) is connected to the Left riser (SXB-1B) via 16x+16x. Socket 01 (CPU2) is connected to the right riser (SBX2) via 16x only.

The RSC-R2UW-4E8 riser card in your box takes the aforementioned 16x+16x connection and bifurcates it to four 8x connections. They are both physically and electrically 8x.

Those slots physically do not accept 16x GPU or Phi cards, there's no logical limitation.

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