Gigabyte Radeon HD4850 review - The Card
Author: Luka Rakamaric
Date: 16 Jul 2008

Today we are taking a look at the weaker of two models, that is equipped with GDDR3 memory, while the 4870 will use brand new GDDR5 that enables 512 bit throughput over a 256 bit bus. The 4850 is a pretty small card, and you just can’t believe that all that we have talked about is cooled only with a single slot cooler. When you consider that this card is supposed to be a direct competitor to the 9800GTX, looks better be deceiving.  The new Radeon uses more power than its predecessor, but still the power section of the card is not very complex. There is a dual phase PWM, eight MOS transistors, exactly the same as the 3850 and 3870 cards. There are eight memory chips, which are manufactured by Quimonda rated at 1.0 ns and clocked just below the 1000 MHz mark. With a 256 memory bus, the total memory bandwidth is around 64 GBps, which is substantially less than the new NVIDIA cards with 512 bit busses. Still, the 4870 using GDDR5 memory will double that because of the design of the GDDR5 chips. Since the card uses a single slot cooler, the 625 MHz core clock is not surprising, but we have to remember that the die has around 50% more transistors which need to be cooled.

The cooler performance is a bit of a puzzle. It keeps the card stable even with raising the clocks to the 700 MHz range, but it can’t really cool it down,  it just keeps it from overheating. We measured over 90 degrees on the hottest part of the card in an airconditioned room while overclocked which is not pleasant, but since the card is not showing any symptoms we will declare it adequate. If you plan to use your PC in hot spaces or overclock significantly, a custom cooler should be a must. On the noise side, the card remains quite silent during all working modes, most of which is due to a complex fan design with 19 fanblades. In theory, the more blades you have, the more stable pressure the fan produces and that greatly limits vibrations.

Testbed system used:
- Intel Core 2 Quad QX9650
- ASUS Striker 2 Extreme for single card and SLI performance
- Gigabyte X48T-DQ6 for CrossFire
- OCZ PC3 1600 Intel Extreme Series 2x1GB
- Western Digital RaptorX 150 GB
- PC Power & Cooling TurboCool 1KW-SR