Core i7-2600

35X - 4 cores active
36X - 3 cores active
37X - 2 cores active
38X - 1 core active

On top of this, if the bios allows, you can get a +4 overclock on top of the base results above.

39X - 4 cores active
40X - 3 cores active
41X - 2 cores active
42X - 1 core active

In your first screen shot you can see the multiplier getting up to about 41.5. If you use the Task Manager Set Affinity... function, you might see it go a hair higher if you lock 1 thread of P95 to a single thread of your CPU so it doesn't bounce around.

There is always lots of background activity on a windows PC so you will never see the full 42 multiplier for the entire 1 second monitoring period. Cores wake up and the maximum goes down. Cores go back to sleep and the multiplier goes back up to 42. This is going on hundreds of times a second. ThrottleStop accurately reports the average multiplier when this is happening.

Unfortunately this CPU is limited by Intel and there is nothing software can do to unlock it. You won't be able to ever get the full 42 multiplier when this CPU is fully loaded. It's not possible.