AMD announced four versions of the graphics chips. They range from a low-end 4300 which has 80 cores and dissipates about 7W to the 4800 which has 800 cores and consumes 45W.

Only the high-end part supports GDDR5. Other members of the family support DDR2, DDR3 and GDDR3. The chips have memory interfaces that range from 64- to 256-bits wide.

The former ATI Technologies graphics group has been playing catch up with archrival Nvidia Corp. after missing a product cycle about 18 months ago when it was acquired by AMD.

"They are about six months out of phase," said Dean McCarron, principal of market watcher Mercury Research (Cave Creek, Ariz.). "You end up seeing a ping-pong match between the two of them, and this is the ATI group's return volley," he said.

AMD has rebounded to about a 41 percent share in portable standalone graphics recently, up from about 28 percent a year ago, McCarron said. With the HD4000 roll out, "the race between the two companies will heat up again through 2009," he added.

McCarron said the use of GDDR5 will give the high-end parts "a definite performance boost." However support for the full Microsoft DirectX 10.1 interface is less immediately significant because game developers are still developing titles for the older DX 9 interface.

At the Consumer Electronics Show, AMD will show the HD4000 chips running in notebooks from Taiwan system makers AsusTek and MSI. The chips will be generally available in April.

The HD4000 series is also used as part of the company's new Dragon platform which includes the recently launched Phenom II processors and an AMD 7-series chipset. AMD hopes to replicate in desktops its relatively strong position selling notebook chip sets.