Getting to grips with it
PowerIf our testing of this early engineering sample reflects the
final shipping product, then the manifestation of such power is a
frankly ludicrous
power-draw of
around 320W when placed under sustained load. Some commentators may
argue that's required for two HD 4870 boards, which is true,
but the very fact that the X2 variant plugs into a single PCIe (2.0)
x16 slot can become problematic. Why? Because the 8-pin and 6-pin PCIe
power arrangement provides in the order of 225W to a card; the rest
needs to be pulled from the PCIe slot.
We're not entirely sure what ATI can do to substantially lower the under-load figure, because the single-GPU technology is such that a significant reduction will only come if yields improve, dropping voltages, or when ATI moves, inexorably, to a 45nm process.
Maybe we shouldn't be too critical of the power-draw, not least because the final shipping product may improve in this area, but if only because it's a high-end card aimed at the enthusiast who will, in most probability, be running a 750W+ PSU and other power-sapping components.
What else?
Carrying on where Radeon HD 3000-series left off, the HD 4870 X2 can be coupled with another card for two-board, four-GPU rendering under CrossFireX, which now supports three- and four-GPU speed-up under the OpenGL API.
Two, or more, GPUs from one generation can be combined for extra performance, so, say, a Radeon HD 4870 X2 and Radeon HD 4870 or HD 4850. Of course, adding a slower card negates the benefit of faster-running GPUs. Mix-and-match CrossFireX implementation, therefore, means that you can leverage any 4-series card with the HD 4870 X2, motherboard slots permitting.
Radeon HD 4870 X2 will ship with two DVI connectors capable of dual-link video transfer and HDMI pass-through, availed by a compliant adapter. ATI's multi-GPU-based multi-monitor support is better than NVIDIA's, providing 3D gaming speed-up on two screens - albeit in non-CrossFire mode - and the ability to switch between multi-GPU and multi-monitor mode without engaging in the cumbersome control-panel process used by NVIDIA's GeForce 9800 GX2.
Summary
Radeon HD 4870 X2, targeted at the hardcore enthusiast, is ATI's retort to high-end GPU dominance that NVIDIA has enjoyed for a while now. ATI cannot match NVIDIA' single-GPU performance, so putting two Radeon HD 4870s together, on one board, is the only cost-effective method of providing higher single-board numbers. Think of it as literally two Radeon HD 4870s on one board.
Mooted to arrive at the end of July with a street price we conservatively estimate at $599 or £349, Radeon HD 4870 X2 will fight it out against GeForce GTX 280 for single-board supremacy.
We expect a Radeon HD 4850 X2 to be launched by partners reasonably soon, too, probably with an on-street price of $399 or £250.
On to the numbers, Tonto!
