Uninterruptible power supply issue possibly damaged pc component's.

I have run into a very strange issue as of recent and I'm not sure what to make of it. I have been using an APC es 750 ups for about 3 years now and everything has been working fantastic. I just bought a new pc and upgraded heavily from an i5 2500k to an i7 6700k. I have 8gb of ddr4, Gtx 970, and a evga g2 850w psu. Due to a recent power outage I have discovered for about 7 months now i have had my psu cable plugged into the wrong side of the ups for surge protection only and not the battery backup side (facepalm). It's been about 2 weeks now after I switched to the backup side and the computer has been acting out of the ordinary. The pc is heavily overclocked and I have only had boot issues a few times over the course of the period I have had the pc. As of recent the computer fails to boot with the oc setup almost every other boot. I play alot of csgo and I am constantly monitoring my pc performance and before I switched to battery backup I would use about 40% of the cpu while playing and temps would never push above 50 c ever and usually sat at about 35% Avg. As of now while loading into games the cpu hits spikes upwards of 60 c. In game temps spike and sit at temps as high as 70 c and the cpu load goes beyond 55 - 60% just for cs go which isn't a graphically intensive game and all my graphics settings are at the minimum. Last night I was playing the new release Tom Clancys The Division when all of the sudden the back up battery instantly shut down along with the pc and the back up battery had to be reset. I thought nothing of it at the time and thought maybe I blew a breaker but turns out I did not. After that I turned it back on and continued to play only for it to occur a second time at which point I decided I am buying a new ups with more wattage. I have been reading alot on ups units and modified sine waves. My psu has pfc and I read online that modded sine waves could potentially hurt the psu and possibly damage other components and unfortunately I did not know this. I don't think this can be coincidence that I started haven't problems as soon as I switched to the back up side and I am wondering if the modded sine waves or the psu being faulty damaged my cpu and or others components of my pc. I have checked my water pumped which is a H100i gtx running at max speed and it is working fine. All my case fans are spinning and I even have the radiator for the water pumped sandwiched with 4 fans for extra cooling. I have seen this cpu's core temps go down to as little as 4 c on idle at 4600mhz. Does anyone know if there's anyway I can see if the apc unit has caused damage or has anyone else had this issue?