Maxwell (microarchitecture)
| Fabrication process | 28 nm |
|---|---|
| History | |
| Predecessor | Kepler |
| Successor | Pascal |
Maxwell is the codename for a GPU microarchitecture developed by Nvidia as the successor to the Kepler microarchitecture. The Maxwell architecture was introduced in later models of the GeForce 700 series and is also used in the GeForce 800M series, GeForce 900 series, and Quadro Mxxx series, all manufactured in 28 nm.
The very first Maxwell-based products to hit the market were the GeForce GTX 750 and the GeForce GTX 750 Ti. Both were released on February 18, 2014, both with the chip code number GM107. Earlier GeForce 700 series GPUs had used Kepler chips with the code numbers GK1xx. The GM10x GPUs are also used in the GeForce 800M series and the Quadro Kxxx series. A second generation of Maxwell-based products was introduced on September 18, 2014 with the GeForce GTX 970 and GeForce GTX 980, followed by the GeForce GTX 960 on January 22, 2015, the GeForce GTX Titan X on March 17, 2015, and the GeForce GTX 980 Ti on June 1, 2015. These GPUs have GM20x chip code numbers.
Maxwell introduced an improved Streaming Multiprocessor (SM) design that increased power efficiency,the sixth and seventh generation PureVideo HD, and CUDA Compute Capability 5.2.
The architecture is named after James Clerk Maxwell, the founder of the theory of electromagnetic radiation.
First generation Maxwell GPUs (GM107/GM108) were released as GeForce GTX 745, GTX 750/750 Ti, GTX 850M/860M (GM107) and GeForce 830M/840M (GM108). These new chips provided few consumer-facing additional features, as Nvidia instead focused more on GPU power efficiency. The L2 cache was increased from 256 KiB on Kepler to 2 MiB on Maxwell, reducing the need for more memory bandwidth. Accordingly, the memory bus was reduced from 192 bit on Kepler to 128 bit, further saving power. The streaming multiprocessor design from Kepler was also retooled and partitioned, renaming it to SMM for Maxwell. The structure of the warp scheduler was inherited from Kepler, with the texture units and FP64 CUDA cores still shared, but the layout of most execution units were partitioned so that each warp schedulers in an SMM controls one set of 32 FP32 CUDA cores, one set of 8 load/store units and one set of 8 special function units. This is in contrast to Kepler, where each SMX has 4 schedulers that schedule to a shared pool of execution units. Prior to Kepler, these units were connected to a crossbar that uses unnecessary power to allow them to be shared. On Maxwell, the crossbar was removed as it became redundant. This allowed for a finer-grained and more efficient allocation of resources than in Kepler, saving power when the workload isn't optimal for shared resources. Nvidia claims a 128 CUDA core SMM has 90% of the performance of a 192 CUDA core SMX while efficiency increases by a factor of 2. Also, each Graphics Processing Cluster, or GPC, contains up to 4 SMX units in Kepler, and up to 5 SMM units in first generation Maxwell.
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