All things Navi 10

With quite a bit of evidence from running four 5700 cards in three systems at 3X for days, I'm reversing this position.  Not only does it seem that running at 3X does not impose a meaningful validity penalty over 2X, but also it does give a meaningful improvement in output and power efficiency.  On my Windows 10 systems with three different CPUs it also does not seem to impair interactive responsiveness.

The benefit I see from running 3X vs. 2X varied appreciably among my three systems.  Something about the host characteristics (CPU, motherboard, ...) meant somewhat uneven Einstein productivity at 2X on the three machines, with corresponding differences in GPU Load in the area of 90 to 95%.  Running at 3X, compressed the differences, with all four 5700 cards on all three systems reporting GPU Load very near 98.0%, and a pretty tight range of elapsed times when I kept power limitation at a level which gave reasonably comparable GPU clock rates.

The actual productivity improvement I saw from going from 2X to 3X ranged from about 5% to about 12%, depending on the system.  Up until I had a try at the Radeon VII and the RX 570, I've been an NVidia guy here at Einstein, and in recent applications, the available improvement in going from 2X to 3X on my Nvidia cards was nowhere near that high.  Also the polling method used for detecting GPU support needs of the GPU on the Einstein Nvidia applications meant that the impact on host system interactive performance of adding a task was appreciable. so I did not run at 3X anywhere, and actually limited myself to 1X on my wife's system, which is a hyperthreaded CPU with two physical cores.

Imagine my surprise when I found that my system which currently hosts two 5700 cards with a CPU, which while pretty fast, had only four cores and no hyperthreading, was very happy to run at 3X.  Of course, BOINC would have refused to start the required six tasks had it believed I only had four cores, but I had previously adjusted matters to lie to BOINC, claiming 16 CPUs, as a means of obtaining adequate daily task dispatch limit when this same system was the host for a Radeon VII.

Speaking of that Radeon VII, it is worth mentioning that the system in question is currently appreciably more productive running two RX 5700 cards at 3X than it was running on Radeon VII at 2X  (about 1.8M credits/day vs. 1.6, not nominal but actual).  It currently burns somewhat more power, but there is considerable room to trade a substantial reduction in power consumption for a moderate reduction in credit rate. 

This post is already long, so I'll save other 5700 observations for later, but suffice it to say that at the moment I am quite happy to have done a 100% conversion of my little three host flotilla from RX 570 cards (most recently) to RX 5700 cards.  I must repeat my previous thanks to Gavin and to Mumak for their initial reports that with new driver releases the RX 5700 behavior on Einstein GRP had done a sudden change from almost 100% failure rate to an ordinary invalid rate (currently about 1.6% on my flotilla).