PCB Design

As we said above, the XFX GeForce 6600 GDDR2 differs from the reference card in the color of the PCB only:

We think the color chosen by XFX looks better than the classic green, especially combined with the silvery heatsink of the cooling system. Of course, the use of GDDR2 memory called for a new PCB which differs considerably from the PCB of the GeForce 6600 despite some similarities like the placement of all the eight memory chips on the front side of the card.

This is probably one of the reasons for a rather complex wiring if compared with the GeForce 6600 GT which carries only four GDDR3 chips and whose reverse side is virtually blank. The reverse side of the GeForce 6600 GDDR2 is quite a populated place. There is no seat for a VIVO chip, but you can see a curious sticker that says that the card was made in China. A little above it, the white painted letters tell us the card was “Made in USA”. So where does the XFX GeForce 6600 GDDR2 come from, the USA or China?

The card’s parts may be manufactured in the USA and finally assembled in China, but we are more inclined to think that it is made in China. PCBs are made there and it’s not profitable to transport them to the United States for final assembly.

The power circuit looks more complex than on the GeForce 6600 GT, too. It uses more electrolytic capacitors which are high-quality components from Rubycon and Skywell. The core of the power circuit is two PWM controllers Intersil ISL6549CBZ, one of which is responsible for powering the GPU and the other for the memory chips.

An ordinary NV43 chip (GeForce 6600) of revision A4 can be found under the cooler:

Some earlier chips from NVIDIA used to be marked with a sticker on the die packaging, but now the marking is printed right on the die surface. A 27MHz quartz resonator can be seen to the left of the GPU. It is the main component of the clock generator. The GPU is clocked at 400MHz which is 50MHz higher than specified by NVIDIA and 100MHz higher than the original GeForce 6600.

Eight Infineon HYB18T256161AFL25 chips of GDDR2 memory are employed here. They work at VDD and VDDQ of 1.8V, have 256Mb capacity and 16Mx16 design. So, the total amount of graphics memory on the GeForce 6600 GDDR2 is 256MB and the memory is accessed across a 128-bit bus. The access time of 2.5 nanoseconds means that the chips are rated to be clocked at 400 (800) MHz which is in fact the memory frequency on the GeForce 6600 GDDR2. Once again, this is a great step forward in comparison with the GeForce 6600 with its 250 (500) MHz memory frequency.

It would be an overstatement to refer to the cooler installed on the GeForce 6600 GDDR2 as to an advanced “cooling system”. It is just a flat U-shaped plate with some ribbing and a tiny fan under a translucent air-directing casing. The efficiency of this solution is low, but more elaborate cooling is not in fact necessary here – the 0.13-micron GPU is clocked at 400MHz, so its heat dissipation isn’t too high. The fan bears a holographic sticker with an XFX logo, but the design of the cooler is an exact copy of the reference one.