ATI CrossFire Xpress 3200

ATI CrossFire Xpress 3200
Architecture	Dual-chip North Bridge: ATI RD580 South Bridge: ATI SB600
Connection between North/South Bridge	PCI Express x4 (2GB/sec)
HyperTransport Support	16-bit/1GHz
PCI Express lanes	40 total
Mult-GPU support	Yes, CrossFire North Bridge: 2x PCI Express x16
PCI Support	Yes, 6 devices
USB 2.0 support	Yes, 10 ports
Serial ATA Support	Yes, SATA II Controller
NCQ Support	Yes
Serial ATA ports	4
Parallel ATA channels	1
RAID Support	Yes, 0, 1, 10
Ethernet Support	No
Network Security	None
Audio Support	HD Audio (Azalia)

As we just stated, ATI’s “new” Socket AM2 chipset is actually largely the same as ATI’s previous CrossFire chipset for Socket 939 – ATI has made no changes to the CrossFire Xpress 3200 North Bridge – only the new AM2 chipset sports ATI’s brand new SB600 South Bridge, which replaces the ATI SB450 South Bridge used previously (although many motherboard manufacturers including ASUS opted to use ULi’s 1575 South Bridge instead of SB450 on their CrossFire Xpress 3200 motherboards.

If you recall, CrossFire Xpress 3200 supports up to 40 lanes of PCI Express connectivity, enough to run two x16 PCI Express graphics slots. The other 8 lanes are split between ATI’s chip-to-chip interconnect and expansion, with 4 lanes going to ATI’s A-Link Xpress2 chipset interconnect, which connects the RD580 North Bridge to its SB600 South Bridge, while the remaining four lanes are devoted for expansion cards.

One trait of their RD580 North Bridge that ATI is particularly proud of is the fact that their RD580 North Bridge handles all 40 PCI Express lanes. ATI argues that NVIDIA’s architecture is less efficient due to the fact that the interconnect connecting NVIDIA’s North and South Bridge could become a bottleneck. We agree that ATI’s solution looks more elegant on paper, in reality though there have been no cases where NVIDIA’s architecture has presented a problem. In addition, ATI’s solution was due in part by necessity, by integrating all of the PCI Express lanes into the North Bridge, ATI’s motherboard partners can still provide full 16 lane operation to both graphics slots while using a third-party South Bridge from ULi.

Speaking of the South Bridge, ATI’s new SB600 chip is much improved in comparison to its predecessor. Whereas SB450 lacked support for even basic features like Gigabit Ethernet and 300MB/sec Serial ATA with NCQ, SB600 is stuffed with goodies.

First, ATI claims that SB600 has resolved the nagging USB performance issues that plagued SB450. In addition, ATI has finally added support for 300MB/sec Serial ATA transfer rates as well as Native Command Queuing. Up to four Serial ATA hard drives are supported. Finally, with SB600 ATI has integrated support for RAID Levels 0, 1, and 10.

Interestingly enough, ATI’s Xpress 3200 chipset omits an integrated networking engine. That’s right, ATI doesn’t even provide a basic 10/100 Ethernet controller with their Xpress 3200 chipset. Instead ATI relies on the motherboard manufacturers to implement whatever networking solution they wish. This makes things more flexible for the motherboard manufacturers, as they can choose whichever solution they’d like, but one downside is that this decision could lead to a wide variance when it comes to networking performance on various Xpress 3200 motherboards. For instance we wouldn’t be surprised to see a motherboard manufacturer or two drop a PCI-bound (rather than PCI Exress) GigE network controller on the unsuspecting public.