A Closer Look

On the bottom of the waterblock you can see several contact spots. Both GPUs, the PCI-Express bridge chip, the memory chips and the voltage regulation circuitry is cooled. Unfortunately there are more memory chips on the other side of the PCB which are not cooled. This will essentially limit the memory overclock to that of the other side.


A single CrossFire connector is present to link this card to another HD 4870 X2 or HD 4870. CrossFire will work with any HD 4870 / 4870 X2 from any mamn


The card has one six-pin power connector and one eight-pin power connector. Both are required for operation.


The GDDR5 memory chips are made by Hynix and carry the model number H5GQ1H24MJA. With a latency of 1.0 ns, they should be good for at least 1000 MHz.


The PLX Technology PEX 8647 is a PCIe Gen2, 5.0GT/s 48-lane, 3-port PCIe Switch.
While the bridge chip on the HD 3870 X2 supported only PCI-E 1.1 transfers, this one has full support for PCI-E 2.0, and also offers new features like Dual Cast and Read Pacing.


Two AMD RV770 GPUs are working together on the HD 4870 X2. The GPU has a die size of 256 mm², is made in a 55 nm process and sports 956 million transistors.