A Closer Look

The cooler installed on the PowerColor HD 4890 PCS is provided by Zerotherm. A base makes contact with the GPU core and four heatpipes are used to transport the heat away to a large number of cooling fins.


The memory chips are cooled by little metal plates that act as heatspreader. Since they are located directly below the heatsink there is always some air flowing around them which helps with cooling.


The little heatspreaders are attached using an incredibly strong thermal tape. Please do not try to remove them, you might rip the memory chip off the board instead. Despite the color, the heatspreaders are not made from copper as you can see on the second picture where I scraped away some paint.


Two six pin PCI-Express power connectors are required to supply additional power to the graphics card.


The voltage regulator area is cooled by a tall copper colored heatsink, which is not real copper either. Still, it does a great job at keeping the VRMs cool.


The GDDR5 memory chips are made by Qimonda and carry the model number IDGV1G-05A1F1C-40X. With a cycle time of 1.0 ns, they are specified to run at 1000 MHz.


PowerColor has made some changes to the voltage regulation circuitry. Instead of dual Volterra controllers, they use a single OnSemi NCP5388. It does not have an I2C interface so software voltage control will not be possible.


This is AMD's RV790 GPU. It is identical to RV770, except for improved signal routing which allows higher overclocks. It is made on a 55 nm process at TSMC Taiwan, the 959 million transistors occupy 282 mm² of die area.