GeForce 800M series combines Maxwell, Kepler

Spring is almost here, and yet again, Nvidia has marked the equinox (or just about) with a series of new mobile graphics processors. The GeForce 800M family spans six new models, introduces power-saving mojo called Battery Boost, and features both Nvidia's latest Maxwell architecture as well as the older Kepler architecture. Here are some specs for the GTX-branded members of the family:

Model Stream
GeForce GTX 880M 1536 954 Yes up to 4GB GDDR5 2500 256-bit 160GB/s
GeForce GTX 870M 1344 941 Yes up to 3GB GDDR5 2500 192-bit 120GB/s
GeForce GTX 860M 1152 or 640 797 or 1029 Yes up to 2GB GDDR5 2500 128-bit 80GB/s
GeForce GTX 850M 640 876 Yes up to 2GB GDDR5 2500 128-bit 80GB/s

The GeForce GTX 880M and 870M are both based on the older Kepler arch, as are "some" of the GeForce GTX 860M parts, Nvidia tells us. Other GTX 860M models will be based on the same Maxwell-infused GM107 silicon as the GeForce GTX 750 and 750 Ti, which debuted on the desktop just under a month ago. The GM107 chip has only 640 stream processors, but it's clocked higher, and its architecture is more efficient. GM107-based versions of the GTX 860M might therefore be as fast or even faster than the Kepler-based ones.

The lineup also includes the GeForce GTX 850M, which is GM107-based, and the GeForce 840M and 830M, which are powered by the GM108, a smaller Maxwell chip that hasn't yet cropped up on the desktop. Nvidia didn't give us complete specs for the 840M and 830M, but it says they have 64-bit memory interfaces and can accommodate up to 2GB of DDR3 memory. They supplement the GeForce 820M, an entry-level offering that's already been around for a little while. (That model is based on the old Fermi architecture.)

On the performance front, Nvidia touts across-the-board double-digit improvements when comparing the newcomers to the GeForce 700M series. The GTX 880M and 870M are 15% and 30% faster than their predecessors, the company claims, while the GTX 860M and GTX 850M are 40% and 60% faster than corresponding 700M-series parts, and the 840M and 830M are 35% and 25% faster than their forebeards. It's not clear if the figure for the GTX 860M applies to the Maxwell- or Kepler-based model.

All of the GeForce 800M parts launching today feature Battery Boost, a novel power-saving scheme that combines the granular power states and clocking capabilities of Kepler and Maxwell parts with a frame-rate targeting scheme. Nvidia deliberately declined to go into too much detail, but as I understand it, Battery Boost sets a frame-rate target through the GeForce Experience software, which controls in-game graphical settings, and runs the GPU only as fast as it needs to meet that target. Setting a low frame-rate target can also lead the CPU to kick into a lower power state, since it has less work to do, thus saving even more power. Battery Boost doesn't control CPU clocks directly, however.

Battery Boost in action. Source: Nvidia.

In a best-case scenario, Nvidia says Battery Boost can yield a two-fold increase in gaming battery life. There's only one caveat, as far as I can tell: the game must be launched with the system unplugged, since the GeForce Experience software can't adjust graphical details on the fly. Non-gaming battery life isn't affected, but that shouldn't be an issue. These GPUs all support Nvidia's Optimus switchable graphics technology, which falls back to the Intel IGP and disables discrete graphics when the system isn't running a game (or a graphically demanding application).

You can expect to find the new GeForce 800M-series GPUs inside systems from Alienware, Asus, Gigabyte, Lenovo, MSI, and Razer. Nvidia says availability should begin "immediately" for certain models, although we may have to wait for some manufacturers to announce systems first.

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