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juanrga :
Stutter is a latency problem when one or more frames take more time to render. Overclocking RAM reduces access latency and this can eliminate stutter if the bottleneck was memory. Check the graphs, specially the i3 numbers. Average increased by 25%, but minimum increased a huge 59%. which reduces the possibility of stuttering.
Timings reduce latency, Mhz increase effective bandwidth. Isn't that the rule of thumb? Something that is bandwidth starved might not be latency sensitive at all. If you increase bandwidth, then you're talking about something different.
And it has nothing to do with what I said anyway. Increasing effective FPS (min or max) does not decrease the *chance* of stutter, it actually increases it! That is why it's important to measure how the frame generation is distributed along a benchmark run and then inversely correlate the information you get.
8350rocks :
Stutter is a problem that is not due to latency (cas level) or bandwidth (MT/s), it is due to the CPU not providing the data quick enough due to overall workload. RAM latency has virtually nothing to do with that at all, which is why most CPUs see single digit performance gains even making massive leaps in RAM frequency or cas level.
There are some games on very dated engines that are extremely single core sensitive that see higher gains, like FO4 for example, or Arma3, but beyond those outliers...going from DDR4-2400 to DDR4-3600 (50% increase in MT/s) only yields something like 6-8% performance gain on Intel systems, even if you keep the cas level the same (total RAM latency).
I am not discussing CAS latency, but
frame latency. If a CPU (with a given GPU) does 100 frames per second, then it takes 0.01 seconds to draw each frame on average. The frame total latency T is the sum of a compute contribution plus a memory contribution. If the game is compute-bound, then T ~ T_comp. If the game is memory bound, then T ~ T_mem.
This T_mem is given by the time to access the data plus the time required to move the needed data to the CPU,
T_mem = T_access + T_transp
increasing memory clocks reduces both latencies, because the increased bandwidth reduces T_transp, and because CAS latencies are relative, not absolute, and increasing clocks reduces T_access through the formula given by goldstone77.
Stuttering is the reflection of some instantaneous higher-than-average bottleneck that increases the frame latency above the average.
The game tested by jdwii is memory bound and the more probable cause for stuttering is some instantaneous higher-than-average bottleneck when accessing memory. Increasing memory clocks reduces the bottleneck, which affects both average latencies and the possibility of stuttering. That is also why minimum framerates got much higher increase than average framerates when going from 1333MHz to 2400MHz.
Things go to other side on compute-bound games. In those games stuttering is generated because at some instant there are not enough compute resources and one or more frames take more time to render (higher-than-average frame latency). Stuttering in this case is solved by increasing the compute resources, e.g. moar cores or OC the CPU.
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