Hi, sorry for a very late answer.
I am using an ASUS X550IU which also has the odd FX-9830P + RX 460 combo.
I have just recently applied new thermal paste to the APU, and my CPU in windows is pending between 3492 mhz and 3792mhz. Also the temps are in the 50-range when testing a session of Cinebench R15. If possible, go for new thermal paste.
There is another way to change settings in BIOS though, using a modded bios. This is
very dangerous though, as some settings in the BIOS are not to be messed with (trust me, I am on my 2nd motherboard after I accidently bricked my first MB unstable in the bios). 200$ gone...
I used the BIOS from this thread:
https://www.bios-mods.com/forum/Thread-Asus-K550IU-X550IU-Bios-Request
If you uncheck the CPB-setting your CPU will only reach 3ghz, but will be a lot cooler and also more stable. And no annoying fan sound.