Few months ago my corsair CX430( Not V2 ) started acting weird and therefore my system started getting restarted randomly. I realize it is the PSU b'coz when I replaced it with a cheap one everything was working fine. So I send it for replacement and they send a new one. Now the same problem starting to reappear again. I send an mail to both companies & they both blatantly said that there is a good chance my UPS & PSU are not compatible. Reason is simple . PSU accepts pure sine wave. and my basic APC (Back UPS 650VA) gives stimulated sine wave. The strange part is that for more than two years both products functioned without any hassles.

what are my options now? The warranty for both has been expired. I cannot put a cheap PSU b'coz it will not give enough power to my system for sure. I cannot opt for a pure sine wave UPS b'coz it's out of my budget. If I opt for a cheap UPS will it work ??. Can anyone suggest any solutions ???