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Radeon HD 4200 Enhancements

Updated: AMD 785G: The Venerable 780G, Evolved
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For years now, we've wished that someone would come out with an IGP capable of handling today's games at reasonable detail settings and at resolutions of at least 1280x1024, which is the lowest resolution at which I'd be happy playing.

The Radeon HD 4200 built into AMD's 785G chipset is, unfortunately, not the realization of this dream.

Don't get me wrong. The 785G is a great IGP, but it's pretty much exactly as great as the 780G before it, as the performance-oriented specifications have remained essentially identical: 40 stream processors, four texture units, and four ROPs. The 785G even runs at the same clock speed as the 780G, 500 MHz.

So what's different abut the 785G graphics processor? DirectX 10.1 support is the obvious answer. And, well, not much more as far as hardware specifications go:

AMD 78x and 79x Graphics Processors

AMD 785G AMD 780G AMD 790GX
Integrated Core RV620 RV610 RV610
DirectX/OpenGL 10.1/2.1 10.0/2.1 10.0/2.0
Shaders/TU/ROP
40/4/4
40/4/440/4/4
Graphics Clock 500 MHz 500 MHz 700 MHz

As suggested by the name 785G, this is an incremental upgrade. The DirectX 10.1 enhancements will not offer any immediate performance benefits for the end-user. DirectX 10.1 features can be enabled, but these won't likely speed up the frame rates, as we will demonstrate in our game benchmarks.

While the chipset's 785G designation reflects minor improvements, the name of the Radeon HD 4200’s GPU is quite a bit more provocative. Given its name, one might assume that the Radeon HD 4200 (785G) is superior to the Radeon HD 3300 (790GX), which is not the case when it comes to gaming. The 790GX is clocked at 700 MHz, while the 785G is clocked at 500 MHz. And with everything else being pretty much equal, the 790GX is, of course, notably faster.

The bottom line is that the AMD 790GX and Nvidia GeForce 9400 remain the fastest gaming IGPs out there. As for the good news, most 780G or 785G chipsets should be able to overclock to 790GX specifications or a little higher without cooling modifications, so the end-user can experience passable 1024x768 gaming performance with a little tweaking. This is fine for the casual gamer, but discrete graphics remains the only solution for more demanding settings.

Things might get interesting in the next generation of IGPs if AMD integrates something similar to the Radeon 4350 with its 80 shader processors into a chipset, but I suspect we might not see that for a while yet, as it'll likely require a manufacturing shrink. And when that happens, the day's games will be more demanding and the cycle of pain will continue.

Note that some 785G-based boards will have an advantage over early 780G platforms, because they seem more likely to sport SidePort memory. The cache, consisting of 128 MB of DDR3, serves as dedicated video RAM for the IGP, boosting performance slightly. While some 780G motherboards do offer SidePort memory, it's much more common on the 790GX chipset.

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