Apologies for posting again - can't find my original post.

I am running Intel Turbo Boost monitor and do not see the CPU frequency go above 3.4 GHz (CPU is capable of overclocking and it is set up for overclocking to 4.5 GHz  in BIOS).

I recently reinstalled win 10 on two SSHD configured as RAID 0.  This was necessary due to boot failure after replacing 2 x GTX 970 by 1 x GTX 1070.  Previously I the frequency would go above 3.4 GHz with win 10 on the RAID disk.

I also installed win 10 onto a single HD, followed by the monitor and the CPU frequency goes above 3.4 GHz.

I am stumped as to what is causing this - any ideas?

yes but it was stable before - i'm trying to understand why is it that when it is enabled in bios, overclocking does not occur. the only difference in hardware is the graphics card and pci fan now connected - it was unconnected before without issues, just can't remember why I disconnected it. (compute has not bee used for maybe 6 months)

I guess my next step is to try another hd, install windows, intel turbo boost and see what happens ...

First, I'll say that if this old machine is 100% stable at "stock clocks", that is where I would run it. Seriously.

If you want a little TurboBoost, I think you just leave Intel SpeedStep on (all defaults) and BIOS Over-Clocking OFF.

Then, you have to give it a lot of work to do. Prime95 or OCCT should stress it sufficiently.

Dude, this thing is old and finicky. Set it to stocks clocks and baby-it.

Runs best with everything connected.

Yes, you can use Intel Turbo-Boost. No, it's no OC-ing but it's fine. Must give it lots of work to do with Prime95 and you can see what happens with CPUID's tools.

the thing is, although the cpu is idle a lot of the time, previously the blue bar would go above 3.40 ghz, albeit momentarily....now it will not ... and I don't understand why.

I'll be reverting to the old cards to see if that is the reason, but it's strange that if windows is installed on a single hd instead of 2 in raid, it does, doesn't make sense to me.... and yes, I'm planning to retire it soon. :)

original 970 cards are in; monitor hits 4.00 GHz so back to where I was.  I've set overclock to 4.5 in BIOS so not sure why it' not reaching that but that is for another day.

playing about with RAM timings now.

< I recently reinstalled win 10 on two SSHD configured as RAID 0.

Also noticed this ...

1. SSHD are not true SSD and drivers are notoriously glitchy. 
2. RAIDing (even real) SSDs is not recommended
3. I would not expect doing both to work very well. I think they call that a "Perfect Storm".

Install a single conventional 2.5in SATA-3/600 SSD on SATA,0-1. (240gb-512gb is fine)
Over-Clocking OFF
Clean Install Windows-10
... I bet it will work fine.

No reason to get rid of it that I see. Just config it more normal and it should be fine.

I've had amazing results on my old R3 using lower latency, dual channel- Crucial memory modules @1600 . 

the lower the better imho- latency 9-9- 9