This current challenge is the first time in a long time that I ran WUs that would be bottlenecked by memory bandwidth on my systems. I have a 7600k and a 9700k, and normally see the 9700k have twice the throughput as the 7600k, which is to be expected given that the 9700k has twice as many cores as the 7600k.
The 7600k has 4x4=16GB single rank modules at 3200GHz. The 9700k has 2x8=16GB single rank modules at 3200GHz.
During this challenge, I was getting the following results for Woodall:
7600k: ~64000 second run time and ~228000 second CPU time
9700k: ~56000 second run time and ~404000 second CPU time
I would have expected the 9700k to be slightly more than twice as fast as the 7600k given the doubling in number of cores and the difference in generations, but that isn't the case here.
I am making the assumption that the difference is that the 7600k has 4x4 single rank modules, which in dual channel allows for the two sets of dual channel modules to be treated as two separate ranks and allows one to be written to while the other is read from. The 9700k is not able to do this, and reads will block writes and vise-versa.
I just ordered a second set of matching memory to expand my 9700k, and will report back in a week or so with my results. Hopefully it doubles the speed of the system on large tasks.