A Closer Look

The cooler consists of a copper baseplate that makes direct contact with the GPU and an aluminum array of cooling fins. Both are connected by a heatpipe to ensure optimum heat transfer. Compared to the HD 4850 the cooler is heavier and more complex. In addition to cooling the GPU, the cooler also cools the eight memory chips and the voltage regulator circuitry.


You can use two, three or four of these HD 4870 cards in CrossFire to build an even more powerful rig.


Power to the card is supplied via two 6-pin PCI-Express power connectors, the card will not POST without power or just one power connector connected to it. I found the two connectors to be a bit too close together, which makes it harder to plug in the connectors when the card is installed in the system.


Yum, yum.. nice GDDR5 memory chips. They are made by Qimonda (formerly Infineon) and have the model number IDGV51-05A1F1C-40X. The 40X stands for the data rate of 4.0 Gbps per pin. Effectively this means that chips are rated at 1000 MHz real clock. Please note that GDDR5 offers twice the bandwidth per pin at the same clock than GDDR3/4. So a 256-bit GDDR5 card has the same bandwidth as a 512-bit GDDR3 card at the same clock. This is a key factor in keeping design costs down. As you know NVIDIA uses a 512-bit memory bus on the GTX 280 which dramatically increases total cost. ATI gets the same memory bandwidth with a 256-bit GDDR5 bus at a fraction of the price.


Unlike the NVIDIA GT200, the AMD RV770 GPU is not that big with a die size of 256 mm². Just like all other ATI GPUs the GPU is made at TSMC in a 55nm process.