This is my first time with a modern gaming PC since 2006, and I've got an EVGA 1070 SC that according to online specs should have a GPU at ~ 1900mhz and memory at ~ 4000mhz.
After reading that the latest nvidia reference drivers have clock speed timing problems, I installed the evga overclocking tool "Precision XOC" just to get real stats on what the card is running at. Upon first running it (win 10 64bit) I see it's confusingly running at 200mhz and 600mhz (or was it 800mhz? but super low), which seems completely wrong... Then realized those numbers climb when you actually start running a game. Playing battlefield 1 showed it spike up to exactly the factory setting of 1900mhz (GPU) and 4004mhz (mem) when flipped back to desktip quickly. Then I ran Titanfall 2 and the numbers where about half the speed of the above settings. What gives? is it supposed to be variable like that or should the card be running at "max" clockspeed as long as any game is running, or are different games going to request different clock speeds?  It's really hard to tell if this is the driver bug, or how it's supposed to work. Thanks for any insights :)

It appears to be behaving as designed. 
 
The clocks will change depending on use. For example: If you're browsing, there's no need to have the clocks at full speed - they will reduce. However, if you're playing BF1 (as mentioned) then it makes sense for the clocks to go as high as possible.
 
You appear to have a perfectly fine card working as designed. You can set "Prefer Maximum Performance" in the Nvidia Control Panel to stop the clocks 'downclocking' as often as they do.

Thanks! Comforting to know this is the intended behavior.  I'll also have a look at that Nvidia Control Panel setting.
 
 

Hello Zaqintosh,
as Piers123 has mentioned also, the general recommended setting for power preference is either "Adaptive" or "Prefer Max performance"  keep in mind any clean driver install sets the Nvidia control panel settings back to default.   Another option though the precisionXOC is to use the K-boost feature which forces the max clocks as well.  Please let us know if you need any help.  Take care you two.
 

GPU Boost can vary depending on many factors. What were your clocks running at in titanfall 2? Make sure you're running the latest hot fix driver that helps with low memory clocks on certain factory-overclocked pascal cards.