VR Performance and CPUs- Cores vs Frequency

I feel like I’ll probably write a bunch about performance and VR as we go along since its such a complex topic and there is so much stuff we still need to learn. PC and gaming performance has always been an interesting topic but whereas in the past it was mostly about “can I average 50fps or 55fps on this game?” now it becomes “can I consistently get 90fps 99.9% of the time so I don’t get sick”. 100fps doesn’t matter, 92fps doesn’t matter, but 89fps just sucks. 90fps becomes a really sharp performance line.

So far we only have really preliminary performance data since it depends so much on the content and all of that is in-progress and hasn’t really been optimized. People also haven’t done the work to have their experiences scale up and down depending on the PC they are running on. For example with GPU performance you can do a lot by changing the size of the render target which is normally 1.4x the size of the real physical panels in each dimension (so a total of 1.96 times the pixesl). Having at least 1.4x scale gives you ideal anti-aliasing and sharpness when the panel distortion is applied but if you don’t have enough GPU performance you could reduce that at the expense of some sharpness and graphical quality. Not ideal but it sure beats missing frames.

If CPU becomes the limiting factor your choices are a little more complicated. For one games are traditionally poorly multi-threaded and thus don’t take good advantage of additional cores which is the main CPU performance improvement lately. When dual-core CPUs first came out most games didn’t take advantage of them at all and while the situation has improved quite a bit recently few games seem to take full advantage of 4-core CPUs never-mind some of the 6-core machines that work great as development boxes (compilers LOVE 6-cores now!)

One of the issues in picking the ideal CPU is that CPUs are typically limited by their power consumption / heat generated. So a 6-core CPU is usually limited to much lower frequencies than a 4-core CPU. While it can have overall much more computing resources if the given task isn’t able to keep at least 6 threads busy it will become gated on the performance of a single core which is higher in the chip with fewer cores. So I suspect for many gaming scenarios the high end 4-core CPUs will be better for now than the otherwise better 6-core ones until games can make better use of threads. I’m looking forward to trying out the new Intel Core i7-6700k which is the new 4-core 4.0ghz Skylake CPU that should hopefully be the fastest yet for these scenarios.

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