You mention the multiplier is at x35, and auto before that, do you have any other changes enabled such as pbo or a +mhz boost? I have seen/experienced those kinds of things myself, when trying to tweak a particular setting - too aggressive a pbo, too low a voltage (either on the cpu core side, or infinity fabric/memory controller side)
Also - you say you have the multiplier set at x35 and are now pushing the ram to see what it will OC at, I highly recommend doing 1 at a time, getting the configured completely stable before moving on to the ram, I've had a pbo that wa Sony marginally unstable and only appeared 2 weeks after an oc (event viewer and whea great for narrowing down the specific core) so while your x35 may appear stable now, it may be mostly* stable and throw an error a week from now, which can easily be attributed to the ram changes and lead you down the wrong road for trying trying fix the instability
As for stability testing software I've seen a lot mentioned here that I use myself, r20/r23, ycruncher, core cycler, memtest, 3dmark - all great options - but sometimes just using the pc as normal will bring up issues - I mentioned earlier about the pbo curve, I could have the pc pass almost any test I could think of, but a few days in just watching a YouTube video and light browsing would cause a crash,
hope some of this helps.
