Checking Out the Engine, a Look Inside...

Enough about the looks, time to dig a bit deeper. Let's see what lies beneath the cooling system of the Sapphire Radeon HD 2600 XT GDDR4 graphics accelerator. We are taking a look under the hood by pulling of the cooling solution. As you know by removing the cooling system you are voiding the warranty of your graphics card. So, only for those who don't care about the warranty and want to see what's underneath, with proper handling the heatsink can be removed for whatever reasons. However we don't recommend it, but at the same time we wanted to share the real stuff that makes the Radeon HD 2600 XT what it is today. So let's check together...

To get rid of the cooler, it is just a matter to remove the screws. Doing so you can remove the heatsink covering the graphical processing unit and the memory chips. As the heatsink did cover almost the full PCB, taking it off somehow spectacular to find out what is hidden away, just as what we have seen with the Radeon HD 2900 series. In fact most of the components haven't been visible from the start on the front of the PCB. Once the heatsink was removed we get a good view of the PCB and see that it isn't that overloaded with resistors and voltage regulators. Quite a plain view, with only the RV630 core, memory chips, a row of power regulators and the reference clock regulator. Sober though very efficient and with some real processing potential.

The Sapphire Radeon HD 2600 XT is powered by the new RV630 series line of graphics processors. The RV630 core used is physically the same chip as you will find back on the Radeon HD 2600 PRO video cards and features the unified shader technology, represented by the stream processors. The AMD RV630 chip uses a 65nm manufacturing process for its high performance circuits and has been designed from scratch around the unified shader logic, though along the lines of the more powerful R600 chip. The Radeon HD 2600 XT core works at 800MHz operation speed, actually a bit higher clocked than the Radeon HD 2900 series. And most of the pre-overclocked versions come with the core clock set at 830MHz and ever a bit more.

	GeForce 8600 GTS	Radeon HD 2600 XT
Core Speed	675MHz	800MHz
Memory Speed	2000MHz	2200MHz
Memory Size	256MB GDDR3	256MB GDDR4
Memory Interface	128-bit	128-bit
HDCP Support	Yes	Yes

With the introduction of the R600 core we see that a new era being kicked off which is all about the unified shader technology. This technology is also taken up in the mid-range Radeon HD 2000 series. To incorporate this within the Radeon HD 2600 series we see that ATI has come up with the stream processors which can be used in a unified way as either vertex or pixel shader. That means that these are no longer fixed to just being a vertex or pixel shader, but their function changes according to the processing needs. With a unified GPU architecture some bottleneck between pixel, shader and geometric processing is reduced to a great extend. With the release of the RV630 chip, AMD did a bit of optimizations towards the stream processors to provide some better performance. The combination of greater resource availability and improved scheduling allow for increased efficiency.

The Radeon HD 2600 XT shares s similar external ring bus memory controller as seen on the high-end version. This quite advanced ring bus technology that ATI developed within the RV630 core comes with a great memory bandwidth that can be used to process a substantial amount of data. The ring bus memory controller is a 256-bit internal version but the external interaction is only done with a reduced 128-bit interface. The Sapphire Radeon HD 2600 XT comes with four memory chips in total which are all located on the front side of the board. The memory chips are placed strategically around the RV630 core. Each of these memory chips gives their heat away to the coolers copper sole via elastic rubber-like thermal pads. By cooling the memory chips on their own, it provides extra protection towards the lifetime of the chips in general. The ram chips are placed two by three by three and give a total of 256MB memory.

In total the Sapphire Radeon HD 2600 XT features 256MB GDDR4 memory which is running at 2.2GHz, following the reference settings by ATI. In essence that would mean that some decent 0.9ns memory chips would be just fine for the job. And so ATI has opted for high performance Samsung GDDR4 memory chips, which will allow some freedom for the different manufacturers. These Samsung GDDR4 chips come marked as 0.9ns access time and are therefore rated at 2.22GHz frequency and operating at 1.8V. Being set at only 2.2GHz leaves a small margin for some overclocking. These chips are known to go really fast, and offer great performance. An extra boost of the voltage towards 1.9V would be possible and lift these chips to the next level.