Gamers have enjoyed a love-hate relationship with integrated graphics. The love part comes from the low cost and integrated design of these graphics cores, while the hate emerges when actually trying to play games and dealing with unplayable framerates or game incompatibilities. The AMD 780G chipset, complete with integrated Radeon HD 3200 graphics, looks to change that and supply gamers with a low-cost integrated graphics solution that can actually play games, while doubling it up as a potential HTPC option.
The AMD 780G chipset is designed to supply a gaming and multimedia base for the everyday consumer. Its integrated Radeon HD 3200 graphics engine is the most powerful IGP-based solution yet, and offers playable framerates with most games, while providing exceptional video and multimedia playback, connectivity and support. The AMD 780G Northbridge is matched with the SB700 Southbridge, combining in a low-cost, energy efficient, mainstream system platform with an exceptional feature set.
The 780G Northbridge is an eighth-generation IGP, and one that has integrated a fully DirectX 10/SM4.0 graphics core. It also supports HyperTransport 3.0, one PCIe 2.0 x16 slot, up to six PCIe x1 slots, a DVI/HDMI/DisplayPort w/ HDCP interface, and a Unified Video Decoder. We'll get to the graphics core later, but the UVD supports MPEG-2, VC-1, and H.264 formats, and its decoding acceleration requires very low CPU utilization. HT 3.0 supplies a 2.0+ GHz Interface with 41.6 GB/s of aggregate bandwidth, which provides fast chipset to memory access.
The SB700 Southbridge includes a nice selection of features and connectivity options. It links to the 780G Northbridge using a high-speed A-Link Express II interface, and supplies six SATA 3.0 Gb/s ports with RAID/eSATA, a single PATA channel, twelve USB 2.0 and two USB 1.1 ports, a HD audio controller, ACPI specification 3.0 power management, and HyperFlash IDE-Flash technology.
The 55nm AMD 780G is the first integrated chipset to include a full DirectX 10 core, and its Radeon HD 3200 is the graphics engine that drives the platform. The Radeon HD 3200 sports a unified shader architecture with 40 Stream processors, along with four texture units and four ROPs. This architecture has been taken from the Radeon HD 2400 series, which in turn was also used for the newer Radeon HD 3400 series.
The default clock speed of the Radeon HD 3200 core is 500 MHz and the memory runs at 400 MHz/800 MHz DDR2 effective. This offers a fillrate of 2.0 GB GTexel/s and means that the AMD 780G has slightly lower performance than the 600 MHz core of the Radeon HD 3450, which features the same basic GPU architecture. As this is an IGP solution, memory bandwidth is tied to the system memory and the speed, bus width and latency of the DDR2. The presence of HT 3.0 also helps memory bandwidth, but for that, you need a Phenom processor.
The AMD 780G also includes a UVD (Unified Video Decoder), which along with Avivo HD, helps with standard and HD video playback. Support for MPEG-2, VC-1, and H.264 allows a full 1080p visual experience, and the HDCP compliant outputs ensures Blu-ray/HD-DVD playback. The 780G also supports SurroundView, for dual monitors in standard mode, or up to four displays using a dedicated graphics card.
There is even a design option to include dedicated onboard Display Cache memory, which supplements the unified memory architecture and provides higher gaming performance. You can even overclock the integrated graphics core, and the reference Gigabyte board had this selection in the BIOS (max 1100 MHz). This feature is also available through AMD's OverDrive application, but strangely, this is not adjustable using the Catalyst driver set. In our testing, we couldn't get it much over 700 MHz, while AMD's estimates were at 800 MHz or higher.
One of the more interesting features of the 780G is its support for Hybrid Graphics. This feature provides the AMD 780G with scalable graphics, by enabling both integrated and discrete graphics cores to work in CrossFire mode, thereby increasing performance by letting the integrated Radeon HD 3200 work alongside the dedicated video card. AMD recommends the Radeon HD 3450 for 780G Hybrid mode scaling, as this card best approximates the performance of the integrated HD 3200 graphics.
This sounds great in theory, and it does work, but there are some limitations. For starters, the performance under Hybrid Graphics is limited to the lowest common denominator, and scales to the lowest performing component of the two. That means hooking up a Radeon HD 3800 card would theoretically offer lower performance in Hybrid mode than by itself. We don't have to worry about that scenario, as AMD only supports Hybrid Graphics on the 780G chipset using the Radeon HD 2400 and 3450/3470 video cards.
