Hardware has come across more details of AMD’s upcoming RD790 chipset. The RD790 is the successor to AMD’s previously
released 580X chipset, formerly known as CrossFire Xpress 3200.
This time around AMD is only releasing a new north bridge. The upcoming RD790
is expected to pair with the existing SB600 south bridge.
Nevertheless, the RD790 has plenty of PCI Express lanes to go around.
AMD has equipped the RD790 with 42 PCI Express lanes for plenty of expansion
capabilities. Thirty-two PCI Express lanes are dedicated to two PCIe x16 slots
for CrossFire operation. These lanes can be further divided to deliver four
PCIe x8 slots as well. PCI Express 2.0 will be supported as well.
There will still be plenty of PCIe lanes for other devices or even more PCIe slots.
As the two PCIe x16 or four PCIe x8 slots only take advantage of 32 PCIe lanes,
there are ten remaining lanes with six lanes used for PCIe x1, x2, x4 slots and
integrated PCIe devices and another four lanes used for the south bridge
As far as processor support goes the RD790 supports HyperTransport 3.0
and Socket AM2+. Socket AM2+ will be the new socket used by AMD’s upcoming
Stars core based processors.
It is unknown when RD790 will make its official debut; however, AMD has
been shipping reference boards to manufacturers. There are two reference boards
available: Mako and Wahoo. Mako is the single processor
reference board with support for socket AM2 and AM2+ processors. It will
consist of the RD790 coupled with the SB600. The PCI Express lane configuration
for Mako is as follows: two full-speed PCIe x16 slots, one physical PCIe
x16 slot with four lane signaling for physics, one physical PCIe x4 slots with
two lanes shared between Gigabit Ethernet and SATA and one PCI slot.
Wahoo is the new 4x4 reference board powered by a combination of
the RD790 and SB600. It will support socket 1207+ processors. Wahoo
will feature a slightly different PCIe lane configuration. There will be one
dedicated full-speed PCIe x16 slot while the secondary slot can be configured
for x8 or x16 signaling. The third physical PCIe x16 slot will have eight PCIe
lanes. Lastly it will have one PCIe x1 and one PCI slot.
All PCIe slots on RD790 based motherboards will be compatible with the
PCI Express 2.0 specification.