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Leadtek A6600 GT TDH Preview (GeForce 6600 GT AGP)
By Vijay Anand
Category : Graphics
Published by Jimmy Tang on Saturday, 4th December, 2004


NVIDIA's Reference GeForce 6600 GT AGP

Before we take a look at Leadtek's solution, we show you the design and basic cooling solution from NVIDIA, which would be a good point of comparison for Leadtek's own design .

The NVIDIA GeForce 6600 GT looks all set for Doom 3, but is it? We'll find that out soon enough.


Interestingly, the card sports dual DVI connectors without any additional DVI TMDS transmitters on board. Could the GPU have support for dual connectors within the core? NVIDIA was not able to get back to us on that in time for this article.


The GeForce 6600 GT AGP graphics cards require more power than the AGP slot can quench them. So be sure to hook up a Molex power connector to the card before you power it up.

PCI Express versions of the GeForce 6600 GT graphics cards require no extra Molex power connector because the PCI Express specification for the x16 slot catered for graphics cards can supply up to 75W of power. Compare that to the average AGP slot that can only supply 25W of power and newer AGP 8x motherboards with a maximum of 40W, you'll know why the AGP version requires more juice directly from your power supply. This card is no monster like the GeForce 6800 series so you spare yourself from shopping for very pricey or high capacity power supply units. A decent brand named 300W to 350W power supply unit would do the job adequately for a simple system (but don't hope to get away with those cheap units bundled with most PC casings).

Taking off the small GPU cooler, we can see the GPU and its local frame buffer. The HSI chip is cooled passively by a separate heatsink below.


These are 2ns GDDR3 memory chips from Samsung.


The GeForce 6600 GT GPU up close.

The GeForce 6600 GT is a completely different GPU core from the 6800 series. Featuring eight rendering pipelines and three Vertex Shader units, it has exactly half the hardware prowess of the GeForce 6800 GT and Ultra versions. Memory bus width is also reduced to 128-bit width versus the wide 256-bit memory bus on the GeForce 6800 series. However, this new mid-range GPU boasts of the exact same feature set of its high-end brothers. With the reduced hardware capabilities aimed at the mid-range performance segment, the die size of the GeForce 6600 GT GPU is far smaller at only 156mm² versus a whopping 307mm² for the GeForce 6800 series GPU (the package size is also smaller at 33mm x 33mm). Note that the GeForce 6600 GT is manufactured on the 0.11-micron process and this further lent its hand at die size reduction. Consequently that helped NVIDIA boost the GPU's stock speed to 500MHz without incurring heat build-up issues on a small cooler like that used on this reference board.

On the card, there are only four memory chips that contribute to its 128MB frame buffer. This is because Samsung's GDDR3 parts are only available in 256Mbit capacity, so just four of these chips are sufficient for a 128MB frame buffer. Remember the pricey NVIDIA GeForce 6800 series utilizing an expensive cooler with a built-in heatpipe to cool the memory parts? The memory on the GeForce 6600 GT card isn't any slower than them and yet they are not cooled actively or passively. Part of the reason is to keep the cooler design simple because there are only four memory chips, which don't contribute as much heat as those on the GeForce 6800 series. Even then, we didn't quite like the design of the default reference cooler in terms of aiding heat dissipation from the memory.

The size of the cooler engulfs the memory chips and the air flowing out of the cooler has little effect on cooling the memory. In fact some heat is trapped between the cooler and the memory chips.

Fortunately, the small cooler did not have to cool both the GPU and RAM, but because of its size that engulfs part of the memory chips, heat from those chips do get sandwiched to a certain extent. If the main cooler were slightly smaller, air exhausted from it would have been able to cool the memory as well.

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