Some years ago (nvidia 480Ti times), i had that “Great” idea of going SLI.
Everything worked fine (besides that SLI was a marketing scam). However unreal boiled my two cards to 110C in just minutes after running UT3.
All because out of box unreal always went happy for max fps. That boiled my cards, setting it to 60 fps helped.
What i am saying is that coil whine is unreal still happily pushing your hardware to the limits, which most of current games does not. Unreal Editor is really heavy piece of software, so limit that fps to 60.