NVIDIA 780a: Integrated Graphics and SLI in One
by Gary Key on May 6, 2008 12:00 AM EST- Posted in
- CPUs
One Chipset Fits All
NVIDIA is targeting the 780a as their top chipset for the AMD enthusiast and has gone to great lengths to ensure this is a better alternative than the AMD 790FX. NVIDIA designed this chipset to provide a total platform solution that includes a robust integrated graphics engine or the option to run NVIDIA’s SLI, Quad SLI, or 3-way SLI configuration.
780a Specifics
The NVIDIA 780a SLI chipset is built on TSMC's 65nm process technology. NVIDIA is keeping the exact transistor count private along with several other details concerning the internal layout. That said, the 780a SLI product family includes the 780a SLI MCP and the often utilized nForce 200 chipset that provides an extra 32 lanes of PCI Express 2.0. NVIDIA separates these 32 lanes to provide a single x16 link and dual x8 links for three- way SLI.
The 780a SLI MCP provides 19 lanes in total, 16 are dedicated to the nForce 200 link and the other three are available for x1 slots. NVIDIA 780a SLI MCP sports an intergrated GigE MAC interface, 12 USB 2.0 ports, HDA audio interface, five PCI slots, and support for six SATA drives and two PATA peripherals. RAID 0,1, 0+1, and 5 are fully supported along with native AHCI support now.
NVIDIA uses a highly optimized unified memory architecture (UMA) design, and all graphics memory is shared with system memory with the ability to access up to 512MB of system memory. The core clock speed operates at 500MHz, but unlike the 780G we have not discovered any BIOS options offering the ability to overclock the core. We did try NVIDIA’s performance tool to overclock the core and shaders, but our test sample would lockup at any setting.
Hybrid SLI support is fully implemented on the 780a with the release of the 174.15 driver set this week. Hybrid SLI supports current 8400GS and 8500GT based cards. In early testing, we have seen increases of up to 30% in games with a 8400GS card. The additional card completely changes the game play dynamics of this chipset and allows several recent games to play at 1024x768 or 1280x1024 medium quality settings and still keep the frame rates in the 30FPS to 50FPS range. However, smooth game play at those settings is not possible in Crysis unless you drop the quality setting to low.
NVIDIA integrates their PureVideo HD capabilities into the 780a. PureVideo HD offers hardware acceleration for decoding VC-1, H.264 (AVC), WMV, and MPEG-2 sources up to 1080p resolutions. Advanced de-interlacing is available when using a Phenom processor. We generally found CPU utilization rates and output quality to be near or equal to that of the 9600GT.
On the audio side, the HDMI interface offers support for 8-channel LPCM, provided you install the necessary NVIDIA driver set. Our driver support disks had this driver installation tucked away from the normal chipset installation, so be sure to load it if you want multi-channel LPCM. This feature matches Intel’s G35 chipset and is a far better alternative to the AMD 780G that sports 2-channel LPCM for the HTPC audience.
Rounding out the video capabilities of the 780a is analog output, DVI/HDMI interfaces, and a internal TMDS. The 780a features dual independent displays that allow resolution, refresh rates, and display data to be completely independent on the two display paths. NVIDIA provides HDCP support with on-chip key storage for the DVI or HDMI interfaces but is regulated to a single interface during playback operations. The biggest drawback we found was the 300MHz RAMDAC that only supports resolutions up to 1920x1440 at 75Hz. The DVI support is limited to a single-link TDMS rated at 162MHz pixel clock, which translates to a 1900x1200-resolution limit.
HyperTransport 3.0 capability (5.2GT/s+ interface) is included and is important in getting the most out of the 780a graphics core. With a Phenom onboard, the 780a will perform post-processing on high-definition content and it makes a difference in image quality and fluidity during 1080p playback.
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wjl - Wednesday, May 7, 2008 - link
I tried a Wolfdale 2,6GHz (E8200) with Intel's G35, and it's an improvement already - tho for "serious" HTPC usage, I would probably wait for the G45, which should be out this summer.Sure, Intel chip sets are not flawless, like their drivers also. But Intel and AMD are moving into the right direction, and I wish this would be honoured more when comparison tests like the one here are performed.
The world isn't only Windows, and only gamers - wake up guys. Take the Phoronix test suite if you have to compare and show numbers. I think even this test suite is GPL'ed, so...
Anyway: the ATI/AMD 690G (RS690) will work now with 3D, using only open source drivers - and it's news like these which are really important for the rest of us - not which newest chip set has a few frames per second more or less, which is really ONLY interesting for first person shooters.
Natfly - Tuesday, May 6, 2008 - link
How important is HT3 for the IGP? Is 1080P content watchable without it?
Also, is there an equivalent to AMD's sideport memory that may show up in some 780a/8200 boards?
derek85 - Tuesday, May 6, 2008 - link
HT3 is most important when you watch interlaced contents (1080i) because of the extra HDHQV features require alot more bandwidth than normal 1080p. Theoratically 1080p should be watchable without HT3, but this largely depends on the K8 model you get.I'm not sure about sideport equivalence from NVIDIA, I haven't heard anything related to it and I highly doubt they will be able to come up with one, because that requires modification of their existing blocks which they probably won't bother to spend the time on. If you really want that, just get an AMD board ;)
Natfly - Tuesday, May 6, 2008 - link
Well I was planning on getting a 4850e and have been recently trying to decide between the 780G and 8200. I'd like to get the best IGP performance and also have RAID5 w/out using any extra cards, but that seems impossible at this point. Maybe a manufacturer will pair up 780G with SB750 when it gets released.derek85 - Thursday, May 8, 2008 - link
If you want to max out 3D performance, HT3 is the way to go. HT1 can provide maximum 8GB of bandwidth, HT3 with 1800MHz can provide 14.4GB of bandwidth (2 channel DDR2-800 is 12.8GB). The actual improvement of this reflected in benchmarks such as 3DMarko6 is quite significant (>20%), but nonetheless it is still IGP, so whether you would like to invest more into it is totally up to you.Von Matrices - Tuesday, May 6, 2008 - link
Is my PC at fault or does anyone else notice the horrible compression of the charts on page 6?JarredWalton - Tuesday, May 6, 2008 - link
Fixed... Gary changed the chart sizes but didn't update the HTML (where a smaller width and height was hard-coded). Shame on him. I have had him flogged with a Cat-o-nine-SATA-cords.Mgz - Tuesday, May 6, 2008 - link
in page 4 you have a little typo "we can't really be sure until NVIDI confirms the details"homerdog - Tuesday, May 6, 2008 - link
I appreciate the effort by Nvidia to reduce idle power consumption, but I would much rather see a discrete GPU that doesn't draw so much power when idling in first place. ATI has been making significant strides in this department lately with PowerPlay, and EVERY motherboard/configuration benefits. Having two GPUs with redundant framebuffers is going around your elbow to get to your ******* if you ask me.ChrisRay - Tuesday, May 6, 2008 - link
HomerDog. Not sure I entirely understand your problem with Hybrid Power. Its basically a technology that lets you shut of your discreet GPUS completely. No amount of power saving tech is going to have that measure of impact. ((Or system noise impact)).Your right that every motherboard benefits from power saving tech on discreet GPUs. But the difference in power saving by using a feature like Hybrid power is huge compared to any idle technology existing on GPUS. Browsing from my desktop with Hybrid Power enabled and Quad SLI 9800GX2. My AVG room temp went down 4-5C after 2 hours of web activity from having hybrid power enabled. Thats significant.
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