Palit HD4850 Reviewccokeman - September 11, 2008
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The Palit HD4850 is a PCI-E 2.0 16x video card built upon the ATI RV770 GPU core. Built using a 55nm process, the HD4850 sports 800 unified shaders, 956 million transistors, 512Mb of GDDR3 running through a 256 bit bus. Clock speeds for the HD4850 GPU run at 625MHz with the 512MB of GDDR3 running at 993MHz. Additional features include support for DirectX 10.1, Shader Model 4.1, Windows Vista certification, HDCP capability, PowerPlay technology to reduce energy consumption by monitoring GPU activity and reducing the clock speeds dynamically, and last, but not least, the HD4850 is CrossfireX capable. With the appropriate motherboard just add cards until you reach the performance threshold you are after.
The front end of the Palit HD4850 has three connection points. There are two Dual Link capable DVI ports as well as the HDTV out that can be used in lieu of the DVI outputs. The rear of the HD4850 shows off the pin fin design of the heatsink that covers the power regulation circuits as well as the required 6-pin PCI-E power connection port. If one card does not offer enough performance for you there is always the option to use two or more with a CrossfireX motherboard. There are two Crossfire bridge connections to link the cards together.
The cooling solution used on the Palit HD4850 is a single slot reference design cooler that at first glance appears to be copper throughout its construction. But on closer inspection it appears to be a composite piece. The HD4850 heatsink is almost identical to the HD3850 heatsink and indeed contributes to some of the hot running cards that have been seen. Idle temperatures were in the 80 degree Celsius range at idle with this heatsink. The design of this heatsink discharges air out the front end of the card back into the chassis. If your case ventilation is not up to snuff the temps will rise even further as the heat will just be recycled. The underside of the heatsink is covered with an adhesive plastic covering to keep from shorting out any circuits on the PCB. Nice touch on that as it shows that some thought was put into that part of the design.
Since we have the heatsink off the card we may as well see what's underneath. The thermal interface material for the GPU seems to be the same peanut butter consistency type that has been plaguing the ATI cards for a while. Just removing this and applying Artic Silver 5 netted a 14 degree Celsius improvement in idle temperatures, down to 70 degrees Celsius. The load temperatures decreased by a like amount to 82 degrees Celsius, lower than the stock thermal material allowed at idle. Viewing the fan/temperature relationship with Rivatuner 10 shows that the fan speed at idle is around 1400 RPM and does not start cycling upward until the 80 degree Celsius threshold is reached. The memory power circuit components use a thermal tape to make contact with the heatsink since the gap between the components and the heatsink is greater than the same distance for the GPU core.
Last, but not least, we have what makes the HD4850 tick. The Rv770 GPU. The GDDR3 memory is manufactured by Qimonda and is rated at 1000MHz. I'll have to see if there is left anything for the enthusiast with these memory modules. The power regulation circuits are toward the rear of the PCB and are covered with the full coverage heatsink used by ATI.
Let's get this card installed and see what it's got under the hoo...er heatsink!