Palit Radeon HD 4870 X2 2GB Video Card Review

A Look Under the Heatsink

Both the top and bottom portions of the heatsink come off with very little effort. The bottom portion holds eight thermal pads for the GDDR5 ram modules while the top portion has quite a few additional pads which are used for the VRM modules as well as the memory and PLX chip. For those of you hoping to perhaps use your HD3870 X2 water block on this card, you can forget about it right now. While the mounting holes are very similar, some of the VRM modules are in completely different places than on the older card.


Without a doubt this card carries with it a very complicated PCB layout due to the fact that it houses a pair of cores plus an interface ship. That being said, it is a remarkably clean layout with good high quality solid capacitors and large voltage regulation modules.


The two RV770 cores each have a protective metal shim around them and are placed within striking distance of the PLX bridge chip. The cores are both paired up with 1GB of GDDR5 memory in an 8x 128MB pattern.


Voltage regulation is done by a number of high-quality voltage regulation modules headed up by a pair of Vitec 59PR9853 multi phase SMD inductors which are rated up to 125C operation. These industrial-spec’d modules are supplemented but small Pulse regulators as well.


The real heart of this beast is the new PLX PEX 8647 PCI-E 2.0 Expresslane chip. Unlike the one used on the HD3870 X2, this one uses a full 48 lanes while actually having a smaller die area than the older chip. As we have already discussed this PLX chip handles the majority of the communication between the two RV770 cores while eliminating many of the bottlenecks associated with past switch designs while consuming less than 4 watts.

You can read the whole product brief here: http://www.plxtech.com/pdf/product_b...95_16Jun08.pdf

Finally, the memory used on this sample are Hynix H5GQ1H24MJR T0C modules in an 8 x 128MB pattern around each GPU for 16 modules total rated at 4.0Gbps. ATI has spaced the memory on the front and back of the card.