Inside the 780G chipset

The 780 chipset contains 205 million transistors, that’s over twice the number of transistors in 690G, which contained just 72 million. The majority of these new transistors go towards adding DX10 functionality to chipset’s IGP, dubbed the Radeon HD 3200.

The Radeon HD 3200 IGP is largely based on AMD’s RV620 GPU, which was originally launched in the Radeon HD 3450/3470 back in January. If you recall, RV620 is essentially the die shrunk equivalent of RV610, which debuted in the Radeon HD 2400 family nearly a year ago.

The Radeon HD 3200 IGP features the same unified shading architecture found in the 2400 and 3400 series of GPUs, with 40 stream processors and a 500MHz core clock speed. At 500MHz the 3200 IGP is a little slower than RV610, which ran as slow as 525MHz on the Radeon 2400 Pro, and 700MHz for the 2400 XT (in comparison, the 3450 runs at 600MHz and the 3470 at 800MHz), but some motherboard manufacturers will be offering the ability to overclock the 3200 IGP from within BIOS, allowing end users to make up the difference a little. AMD also says that their motherboard partners are free to integrate their own dedicated frame buffer memory for graphics onto the motherboard, but in the past this feature has rarely been found on other integrated motherboards due to increased costs. Instead system memory is used. The 3200 IGP can address up to 512MB of system RAM.

By essentially taking RV620 and dropping it into an IGP, AMD is able to add support for their Hybrid Graphics technology. Simply pair a discrete RV620 graphics card up to your existing 780G system for a nice boost in 3D gaming performance. Like CrossFire, Hybrid Graphics is only as fast as the slowest component, so you’ll want to pair the IGP up to a similarly clocked and configured graphics card for the most bang for your buck. In other words, while you can pair the IGP up to a 3870, the graphics core will be limited to 500MHz (unless of course you’re willing to OC the IGP). Likewise it would probably be a good idea to pick up a card with 512MB of memory.



As we mentioned on the previous page, 780G supports 1.8GHz HyperTransport 3 when paired with a Phenom processor. The motherboard reverts to 1.0GHz HyperTransport when an Athlon 64 CPU is used. The added bandwidth provided by HT 3 is needed in order to enable high definition post processing, but the other Radeon 3450 Avivo video features are fully supported regardless of the CPU used.


PCI Express 2.0 is also supported. The chipset has 26 PCIe 2.0 lanes total, 16 for the graphics slot and six lanes for the PCIe expansion slots. The remaining four lanes connect the North Bridge to the South Bridge.

Speaking of the South Bridge, the new SB700 South Bridge is largely similar to its predecessor, SB600. AMD has integrated a new dual-channel USB controller to improve transfer rates and have also increased the number of supported USB 2.0 devices from 10 ports to 12. AMD also adds support for 2 USB 1.1 ports in addition to the USB 2.0 ports. The number of SATA drives supported has also been increased from four in SB600 to six in SB700. The SATA controller supports SATA 2 drives with NCQ as well as RAID Levels 0, 1, and 10. One parallel ATA controller is also provided (supporting up to two drives) for older drives.

Other than these changes, SB700 is basically the same as SB600 from a pure features perspective.

AMD-780V

Sitting below the 780G at the bottom end of the 780 family, AMD will also be producing their 780V chipset. 780V runs at 400MHz and lacks support for SurroundView, DisplayPort, Hybrid Graphics, and UVD. AMD is targeting 780V for business/office use, where these features are obviously counterproductive to office productivity. 780V is basically intended for IT managers looking for an affordable alternative to Intel.

For these types of users, the 780V platform should be particularly intriguing once triple-core debuts. The argument from AMD will likely be that you can get a low-cost triple-core platform from AMD at a price similar to Intel’s dual-core.