NVIDIA GTX 750 Ti 'Maxwell' Review

👤by Richard Weatherstone Comments 📅18-02-14
Maxwell Archetecture

Maxwell is the next step along the NVIDIA roadmap after Kepler. The focus with Maxwell is to improve performance per watt, in short improve GPU efficiency. To do this NVIDIA have created a new Streaming Multiprocessor (SM) that improves performance per watt. There are a variety of efficiencies that the new SM performs, including but not limited to logic partitioning, workload balancing, clock-gating granularity, compiler-based scheduling and increasing the number of instructions issued per clock cycle. These efficiencies have allowed NVIDIA to increase the number of SMs to 5 in the new GM107 core. This compares favourably to the two found within the GK107 core. Despite more than doubling the number of SMs, the die size only sees a 25% increase!

Above we can see a block diagram of the GM107 (GTX 750 Ti).

Each of the five SM includes a Polymorph engine and Texture units with the GPC having utilising the raster engine. The huge L2 cache and memory controllers are aligned to the ROPs with all of the above units redesigned and optimised to afford greater power efficiency.

A massive boost in L2 cache from 256KB found in GK107 to 2048KB on GM107 which means that fewer requests to the GPU DRAM are required, once again improving efficiency thus lowering the cards overall power draw. With a few more tweaks at transistor level, the end result means that Maxwell is capable of delivering twice the performance per watt of Kepler but still uses the same 28nm manufacturing process.

Above we can see a comparison between equivalent GM107 and GK107 architectures. Clearly GM107 appears to be more powerful, on paper at least with NVIDIA claiming an average increase of 1.7 X performance. Perhaps the greatest story here though is that this performance gain, with the GM107 based GTX 750 Ti, has a miniscule TDP of just 60W!

While it remains to be seen just how powerful the new Maxwell architecture is, if NVIDIA’s claims regarding the power efficiencies are to be believed they may well have a winner on their hands.

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