Game stuttering after upgrading my CPU

[Light916]

• I upgraded my 6600k to a 9900 and it now stutters in csgo with multicore rendering enables (higher fps: 186 or so, but unplayable choppiness)
• Windows 10 64 bit, 9900, rx 480 (trying to upgrade soon but haven't seen the rtx 3080 in stock long enough). 600W gold standard psu, on an itx build
• Include your entire system specs, including the wattage of your PSU.
• Z390 Aorus I Pro Wifi, updated to latest bios. 
• I am playing CS:GO when I notice this lag, but haven't had the chance to test other games.

Any ideas or tips would be helpful! My cpu is not thermal throttling (had hw monitor open and no core broke 75 degrees), and gpu is running max but not throttling either (this looks like a cpu problem imo.

[Radium_Angel]

2 minutes ago, Light916 said:

Windows 10 64 bit

Was this a fresh install?

 

[Light916]

2 minutes ago, Radium_Angel said:

Was this a fresh install?

 

No i had it on the ssd and swapped mb, cpu, and psu during upgrade. Do you think a fresh install might help?

[Light916]

It looks like one of my cores will randomly jump down to 800 MHz and then back up to the 4.8Ghz it is normally at. It happens for all cores but at different times, could this be it? What could cause this?

[Radium_Angel]

3 hours ago, Light916 said:

Do you think a fresh install might help?

I would think so