We've seen Nvidia play their high-end cards, GTX280 and GTX260, and then ATI rocking the mainstream market with their HD 4870 and HD 4850. These are all excellent cards by all means, but in different price segments. HD 4850 is the cheapest card in this roundup and you can find it priced at €135. Today, with a little help from Diamond HD 4850 card, we remind ourselves of what this card can do.
New RV770-based products pack almost a billion transistors (965 million, core surface 260mm2) and in that respect HD 4850 and HD 4870 are identical. The new GPU is built in 55nm and brings 800 shader processors on both Radeon HD 4000 cards. Compared to the last generation, HD 3800, it’s 2.5 times more shader processors, and the same goes for texture units; HD 4000 packs 40 whereas HD 3800 featured 16. ATI and Nvidia aren’t using the same approach, so we can’t compare the GPUs using shaders, but both approaches get the job done. Just like GT 200, RV770 has ten SIMD clusters (Single Instruction, Multiple Data), and Radeon has 80 shader processors per cluster (GT200 has 24 per cluster), which totals at 800.
Diamond Radeon HD 4850 has all the characteristics of Radeon 4870, except for the speed and memory. HD 4850 runs at 625MHz, whereas HD 4870 runs at 750MHz. The important difference between these two is memory, or memory bandwidth to be more precise. HD 4870 uses GDDR5 memory and has 115.2GB/s bandwidth; whereas Radeon HD 4850’s GDDR3 memory runs at 1986MHz and is capable of 63.6GB/s bandwidth.
Less bandwidth coupled with slower core will definitely affect the performance, but we can’t hide the fact that HD 4850 is still a great card. For their HD 4000 series, ATI (AMD) used 256-bit memory bus, but thanks to GDDR5 running at 3600MHz effectively, it will do a good job locking horns with GT200. GTX 280 has a bandwidth of 141 GB/s, whereas GTX 260 has 111.9GB/s. That tells us that HD 4870 has a higher bandwidth than GTX 260, which features 448-bit bus.
Consumption-wise, HD 4850 is also different from its big brother, HD 4870. HD 4850’s maximum consumption totals at 110W, whereas HD 4870 will draw 160W. It’s important to note that this card is powered through a single 6-pin connector, unlike HD 4870 that needs two of these.
We see that HD 4850 got a single slot cooler and we don’t recommend touching it during operation because it can hit up to 85 degrees Celsius. Still, these are normal temperatures for this card, and although it’s audible – it’s still not too loud.
Diamond didn’t change the reference design, and the only thing giving them away is a small sticker on the TV-out port.
HD 4000 features the newer UVD (Unified Video Decoder) 2.0 engine that enables dual-stream decoding and 7.1 channel (lossless) sound through HDMI. In order for you to enjoy HD, both dual-link DVIs feature HDCP.
Nvidia isn’t the only one planning to use GPU for physics processing, and ATI recently announced cooperation with Intel for its HAVOK engine. Games currently supporting HAVOK API run physics computations on the CPU, but ATI plans on moving it to GPU’s shader processors. GPU’s capabilities are great, and we’ve already seen examples of transcoding apps that use the GPU.
You also get Crossfire/CrossfireX support, so if your motherboard supports that feature, you can link up to 4 cards in Crossfire.