It does matter which slots the memory is in because if they are not in the right slots you will be running in single channel mode instead of dual channel mode. Dual channel gives better performance. The CPU-z Memory tab reports you are currently running in dual channel mode so you must have them in the correct slots. Okay, timings in the Memory tab match what the SPD tab XMP-1600 column shows so that is good.
So what you need to do now is to stress test your current settings to make sure they are giving a stable overclock. Do this: Open HWMonitor on the desktop first thing and leave it open. If you have not done so, download and install Prime95. Run the Prime95 blend stress test for 20 minutes. If the computer blue screens, restarts, locks up or if any of the six Prime95 core workers drops out you fail the test and you are not stable. Also watch HWMonitor as the test runs. If you "Package" temp exceeds 60c, stop the test. If the TMPIN2 temp line exceeds 70c, stop the test. Post back with a pic of HWMonitor after the test is run (if it passes, that is).