Clevo laptop with i7-6700k with 16gb ram died so I bought a new Clevo with i7-8700k and 32gb ram. Neither were/are overclocked.

I moved the old SSD drives over and reinstalled Win10 64 and all the same software.

I was hitting the ceiling on a lot of my old files so I assumed I would have a lot more CPU headroom.

But it just chokes. I can't play any of my old Sonar files without stripping out tons of plugins.

I followed a few of the optimization guides I found, they are all pretty much the same. The only thing I can't do is change the C-state or TurboBoost. For some reason, the BIOS has neither option.

Anyone have any suggestions?

The 8700k doesn't perform worse than the 6700k.
With a well-spec'd/configured desktop machine, you can lock the 8700k's 6-cores at 4700MHz.
By comparison, the 6700k has 4-cores... that can be locked at 4200MHz.
As a point of reference, the 8700k is slightly faster than the 6850k (which is socket 2011-3 w/quad-channel RAM).
The 8700k ushered in a new level of performance for a mid-tier machine.
 
The issue is the limited configuration options (in BIOS) and performance throttling necessary to keep heat in check (in a tight enclosure).  
 
You could take the 8700k that's in the Clevo... put that on a quality Z370 motherboard... and it would be an incredible DAW performer (even at lowest latency settings).
 
There's a 3rd-party utility called Throttle-Stop.
That'll give you some control over C-States and TurboBoost.
Be careful with it... as you can cause overheating.
That's as good as you'll do with a laptop.
 
This is why I'm not a big fan of laptops for use as a main DAW.
If you have high performance expectations, you'll be let down.
 

Jim Roseberry, long time.  This is the old manymanyhaha from way back.
 
It turns out the CPU is being limited to the bus speed.  Working on the solution.

Has been a while... (I'm old)
Good to see you around!

You too man.
 
Coincidental to you mentioning Throttlestop, this video  states if BD PROCHOT is unchecked in Throttlestop, the problem should stop.  It didn't.

The answer was to enable UEFI and reinstall.  CPU clock is normal now

I'm probably blind or lazy but do we have a guide of what things to enable and disable in the BIOS settings. I know its proprietary based on the motherboard but do we have a "general" guide listed somewhere? Thanks

I don't have anything "customized" in the BIOS, other than what to monitor (System).  Same way other than setting the Power Plan to High Performance, disable fast startup and the PC is set to not "sleep". 

Be sure to disable "C-state" processing in BIOS, if that's an option.  It was on by default when I built my system, and it destroyed my audio performance.  Took me a while to figure that one out.  Basically it tells the CPU to clock down (way down) when it's not being pushed, to save energy.  My DAWs all had the CPU barely running, so audio latency absolutely sucked.  Once I disabled the C-state nonsense, everything worked as expected.