hey I discovered nasty bug in KP50 overclocking feature.
I used modified DSP profile with limits 500-900, and it seems it stick to 900 where there are absolutely no need (procesor usage were much under 30% all the time). I tried to fix it just by making profile more switchy (changed up threshold a bit, added substantial but not huge powersave bias, increased sampling rate a half). It was a bit successful - it switched between 720 and 900 most of the time and very rarely got 500/600. For me it's not a big problem since device now doesn't emit any heat which could be felt (name it device is cool), and it before apeared to emit a bit of heat which is enough to feel on stock clock (perhaps undervolting of KP50 helped me). But anybody getting limits upto 1150 would have serious problem - it would be 1150 most of the time, including not used, enabled device - which would substantialy reduce device life, and having it almost permanently on 1150 from full charge until full discharge is I believe enough to have overheat problems and even dmaging the chips (even if it could work well on 1150 for a half an hour without break).

So yes KP50 can break the device on dangerous but not stupidly dangerous overclock settings, because frequency switching don't work as it is said to be. On my side fine since I stopped at adviced limit of 900, even if I can go further. I would not mind the bug for now since the device works more nice, however I would wait for KP51 fixing the bug. I don't believe I have any apps/scripts/modules which would affect frequency switching aside of KP50. Since my device work suprisingly well It's possible that kernel-power-settings report bad values instead of values really beeing too heavy. I did a bit checking under powertop and checked that most offensive application were proximityd, which have to be installed for shortcutd but is useless for me so I disabled it under shortcutd's menu. I have a bit experience with overclocking since my PC has core duo overclocked from 1866 to 2520, including memory pushed up to the limit (since I have poor MB limit were much lower than one guaranted by producer of those kingston hyper-x) - note that core duo is one of best capable of overclock CPUs so I perhaps could go around 3200 but I not needed it so stayed safe (there's substantial gain and have no single instability because prime95 didn't show any errors after 8 hour test).

Back to topic: is there any logs or logmaking tools you want to me make it acquire logs to send you? Do you have any stresstesting application which would not only stress the machine but also well measure stability? I see no prime95 for ARM machines (maybe because it's FPU heavy) and the program is beloved because show substantial instability after seconds medium after minutes and after 12 hour test passed you may be sure there wouldn't be a single wrong calculated innstruction once a month (the algorithm for searching mersenne primes would always give known values - the first thousands of the primes - and it constantly uses values calculated before so it's much better for checking stability than those programs which loop calculation over reseted data again and again). I don't hope getting something same fabulous as prime95 but any good stability checking tools you know is welcome to be linked here - since I'd like to not have application crashed once a month due to small/medium instability due to overclocking. If I could check my phone @900 is fully stable (which is much more than "stable enough") and the KP50 bug would be fixed I may try higher limits (I prefer stable 900 than just working 1350, for sure, and very little noticeable unstability @1100 is enough for me to get upper limit under the frequency).

Anybody would comment or help? Any questions?

EDIT: Also memtest is only for x86, so any memory testing tool for N900 is also appreciated (the faulty memory or memory operation could be very annoying even while not overclocking and should be at least a bit checked before making decision if your device is for service/memory_replace) although I believe I have no problems with RAM. Hovewer it would help many other persons.
PS: do you intend memory overclocking or any overclocking features for another chips than cpu and mpu/dsp in future KP versions?