Ok I just received an extremely strange piece of information from not one but two of my sources. The nature of said leak is so weird that i would urge you take it with a bag of salt. My sources (One and Two) tell me that though the first generation Maxwell GTX 750 and GTX 750 Ti do not currently support CUDA 6. They will be getting CUDA 6 Support. However, here comes the confusing part, they will not be getting UVM support. According to the same sources second generation Maxwell will have both CUDA 6 and UVM support.
Maxwell GTX 750 & GTX 750 Ti do not support Unified Virtual Memory - But will support CUDA 6?
From here on, and for this article only I will assume the leak is correct. Lets see, The first thing to note here is that though CUDA 6 has an essential component of UVM, UVM and CUDA 6 Support are not mutually inclusive. Which would help explain why the GTX 750 and GTX 750 Ti are going to have CUDA 6 Suport but no native UVM. Unified Virtual Memory is a great step towards a more unified architecture and memory scaling. Not to mention that it should simplify code by a lot too. Basically as you may already know, UVM is Nvidia's take on unification architecture as opposed to HSA in AMD's APUs. Where AMD's APUS use a 'truly' unified architecture, Nvidia is attempting to bridge the gap by a more Soft approach.
Now it probably also means that UVM will just be one part of CUDA 6. Which is how it will be possible for the 28nm Maxwell to have CUDA 6 but no UVM. Maxwell's Unified Virtual Memory will basically make the GPU's memory and the system memory one and the same, from the CODE's viewpoint. Now ofcourse in the real world there is still the PCI-E acting as a big bottleneck if you compare it to AMD's HSA implementation. However with the 20nm Maxwell, UVM will be implemented on the architectural level making it more efficient than anything that can be done on 28nm. This is probably the reason the 750 and 750 Ti will not be getting UVM support. There is absolutely no question that Unified Virtual Memory will be a godsent for coders, however I remain skeptical whether it will offer any real world performance increases. Ofcourse UVM aside, Maxwell's architecture itself will surely offer a massive performance increase if the GTX 750 Ti and GTX 750 are any indicators.
— Usman Pirzada (@usmanpirzada) February 24, 2014