At A Glance
Killer performance for $300. Four DVI ports! Faster than a GTX 280.
GDDR3 hurts memory bandwidth. Four DVI ports leave no room for rear exhaust vents.
As a general rule, our belief is that pairing two slow-performing cards using SLI or CrossFire is a bad idea—you’re usually better off running a single faster card. However, the Radeon 4850 X2 delivers astounding performance compared to the single-GPU boards in its price range, spanking the Radeon 4870 and the GeForce GTX 280, with none of the pitfalls that have plagued dual-GPU boards in the past.
At the heart of the board is a pair of ATI’s RV770 GPUs running at 625MHz, just like the single-GPU in the 4850 boards. Each GPU features a full complement of 800 stream processors, which are connected to identical 1GB GDDR3 frame buffers running at 993MHz on a 256-bit bus. Although X2 boards are labeled as featuring 2GB of memory, because the contents of each GPU’s frame buffer must be mirrored, applications can utilize only 1GB of video memory.
Like its 4870-powered predecessor, the 4850 X2 sports ATI’s advanced video decode acceleration, allowing you to view fully accelerated picture-in-picture Blu-ray discs. It’s fully compatible with multiple-monitor displays, and we love that this board features four DVI ports for multi-mon madness.
In our performance testing, the 4850 X2 unseated the fastest single-GPU videocards, the GeForce GTX 280 and Radeon HD 4870, in almost every benchmark. The exception to the rule was Crysis at high visual-quality settings and high resolution. When running at 1920x1200 with 4x antialiasing and the visual-quality settings cranked to Very High, we hit the 4850 X2’s memory bandwidth wall. Despite running at a higher clock speed than the 4870-family boards, the GDDR3 on the 4850 transfers half as much data per clock cycle.
With a street price that’s less than $300, the 4850 X2 is a great deal for owners of lower-resolution 22-inch monitors. However, if you use a 24-inch or 30-inch panel, it’s probably worth ponying up for a card with a peppier memory pipeline.