My i5 3570k doesn't struggle with anything that's on it, my i7-3770K sees even less of a struggle and its running considerably more. I got my i7 on ebay for $50.
There's very little difference between the 2 i5's for the most part, granted you'll show ability to get higher fps, but my i7 already gets 300fps on cs:go, heavily modded (138 4k/8k, flora/fauna, cities, enb, 4k DSR) skyrim barely gets my i7 to 55% on max ultra settings, MGS:V at max settings gets 54% with gpu at 98%. Honestly, Ivy Bridge are still very much viable as a cpu base even put up against modern titles and gpus.
Cpus are notoriously hard to kill except by heat, there's enough components and circuitry between the cpu and psu that voltages are very rarely an issue. You'll fry a mobo before destroying a cpu. So if you haven't had your fingers in the socket, that basically leaves software of some sort, be it apps you approve of, or the malware you don't.
My old standby is spybot - search and destroy. It'll do the one thing that most all other vifus/malware won't, and thats lock up the hosts file. The other is malwarebytes. Quite often 1 will pick up on something the other missed, no software being perfect.
I'm not so sure temps are the issue, that's usually reserved for throttling, which slows the cpu clocks, not add high % usage. Sounds much more like a malicious software problem, jacking up cpu % with additional information being broadcast on the net to multiple fishing sites.