Before we get into game benchmarking, let's run through some synthetic tests to get a better sense of the GT 640's capabilities.
|GeForce GTS 450||25||25||98|
|GeForce GTX 550 Ti||29||29||98|
|GeForce GTX 550 Ti Cyclone||30||30||103|
|GeForce GT 640||29||29||29|
|Radeon HD 7750||26||13||72|
The GeForce GT 640's low memory bandwidth is no handicap in these texture filtering tests. Kepler's relatively strong texturing performance puts the GT 640 ahead of the Radeon HD 7750, especially in FP16 filtering, where the AMD card's peak theoretical throughput is half its integer rate.
|GeForce GTS 450||783||98|
|GeForce GTX 550 Ti||900||98|
|GeForce GTX 550 Ti Cyclone||950||103|
|GeForce GT 640||900||29|
|Radeon HD 7750||800||72|
In this tessellation test, the GT 640 manages to outpace the 7750 and the older GeForce GTX 550 Ti Cyclone—a card that has both greater memory bandwidth and higher peak theoretical rasterization performance. This isn't the first time we see a Kepler part zoom ahead of the competition in this test.
|GeForce GTS 450||0.7||98|
|GeForce GTX 550 Ti||0.7||98|
|GeForce GTX 550 Ti Cyclone||0.7||103|
|GeForce GT 640||0.7||29|
|Radeon HD 7750||0.8||72|
The GT 640 falls behind in these tests, which are chiefly designed to gauge its shader performance. Considering these three cards all have roughly comparable peak theoretical throughput, the GT 640's low memory bandwidth is likely a bottleneck here.
Of course, the Radeon HD 7750 has a huge advantage in LuxMark regardless, even over the GeForce GTX 550 Ti. We've seen a similar pattern with high-end Radeon HD 7800- and 7900-series GPUs stacked up against the GTX 680 and older GeForces in this test. Nvidia has told us it doesn't optimize its drivers for LuxMark, which likely explains the discrepancy.
Let's now see how things shake out in some actual games.
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