PC fans running high when they didn't use to while gaming

[Jaexyn]

I've been playing Red Dead Redemption 2 and Red Dead Online since they came out for the PC. Up until about a week ago, my PC was running everything just fine at the game's recommended settings (most everything at Ultra), even while having a video playing on my second monitor. Now, after about 10 or so minutes in game, my fans kick on high. I'm seeing core temps in the 70s.

My idle temps are in the high 30s-low 40s, FYI (if that helps with anything).

I have a Digital Storm PC (pre-built). It has: i7-8700K (6-Core) 3.70GHz, ASUS ROG MAXIMUS X HERO , GeForce GTX 1080 Ti 11GB (Performance Edition), 32GB ram, AIO Corsair H100i GTX, 850W Corsair PSU, and it's all in their Lumos chassis (glass paneled). It's about 1.5 years old and has never given me any issues.

With only having this window open that I'm typing in and HWMonitor up, my temps are at 48-60, with Core 1 always being the highest. The difference between core 1 and the rest is around 2-7 degrees. In Task Manager at the moment, Firefox is the biggest CPU hog but only at ~8-9%. Next highest would be the Desktop Window Manager itself or HWMonitor at ~1%. My GPU temps in the situations where the fans kick on high sit around 74.

I've spoke with the Digital Storm tech guys (good group of dudes) and am waiting to hear back since the last thing they recommended I try didn't do the trick. They've had me un/reinstall AI Suite and run the Fan Xpert software, tried setting the Fan Speed Profile in the BIOS to silent, and even updated the BIOS to the most recent one found (October of 2019), none of which has seemed to do anything significant.

Immediately before this problem started, I hadn't done anything to my system that I feel would warrant changes like this, e.g. system updates, install new hardware or software, etc.

I have no ideas other than maybe redoing the thermal paste, and it seemed like they were a bit stuck too. Hoping to get a different diagnosis or treatment. Please let me know if I can provide any other info that might help. I'm currently at work so I won't have access to the PC for a few hours if there is anything hands-on I would have to check for answering questions, but I'll definitely be able to do so when I get home.

Thanks in advance.