Sapphire HD 4890 Toxic/Vapor-X Reviewccokeman -
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Let's start off with the HD 4890 Toxic. The Toxic is built upon the R790 core manufactured using a 55nm process. It features 956 million transistors, 800 stream processors and 1GB of GDDR5 memory run through a 256 bit bus. The Toxic is meant to be used in a 16x PCIe slot and is PCIe 2.0 capable. While the stock clock speeds on the reference HD 4890 come in at 850MHz on the core and 975 on the memory the Sapphire Toxic edition comes in at a much higher level at 960MHz on the Core and 1050MHz on the 1GB frame buffer. The cooling solution employed by Sapphire to keep this card cool is the same that is seen on the Sapphire Atomic I looked at just a few short weeks ago. In fact the only difference between the cards visually is the decoration on the heatsink shroud. Its what lies underneath that make the difference.
The front end of the Toxic had the display connections and uses what is pretty much the norm for cards coming out with 2 Dual Link capable DVI ports and an HDTV output. The rear view shows that the power requirements are a little steeper with the inclusion of both a 6 and 8 pin power plugs. With the added power I would have to expect a bit more clock speed at the top end will be available considering the already 110MHz increase in core clock speed. The fin array for the Vapor X cooling solution is just barely visible in this picture. The Toxic is CrossfireX capable evidenced by the dual bridge connections. To use this multi GPU solution you will need a motherboard that supports CrossfireX and another Toxic to make it a pair or more with the appropriate AMD 790FX based motherboard .
Once you pop the lid off of the Toxic you can see just how closely the family resemblance to the Atomic Edition HD 4890. To cool this card down you have a hybrid solution that uses a vapor chamber to pull the heat from the GPU and memory. The heat is then transferred to the heatpipes and to the aluminum fin array to be carried out the back end of the chassis. The voltage regulation circuit employs an aluminum block the benefits from the air flowing through the shroud to keep the mosfets cool under load.
The HD 4890 Toxic is based on the R790 core which uses improvements in the architecture to improve upon the successful R770 core. The 800 stream processors 16 ROP's and 55nm manufacturing process are the same throughout the line up. The clock speeds on the Toxic come in a few ticks below the Atomic at 960MHz on the core and 1050 on the 1GB of GDDR5 memory. The Memory used on the Toxic is made by Qimonda and is rated for operation at 1000MHz. The Atomic uses the same modules and the Atomic flew past 1200MHz. Hopefully the Toxic will be no different.
Hopefully the Toxic will deliver a level of performance almost equal to that of the Atomic. Let's move on to the Vapor-X model to see just what makes it that much more different as both models use Vapor Plate technology.