There is nothing weird about it, afterburner it self does not render anything using GPU. Perhaps you are just using a aftermarket card that does include OC in the BIOS from the manufacturer.
GTX Cards have profiles and switching between them changes the way boost and OC works. Simply put, the computation does not trigger a profile used when playing games or using hardware acceleration.
Once I trigger the change (for example media player with HW acceleration) the driver does increase clock of the card and enables boost to increase it even more.
I suppose most users use aftermarket cards and those are OC by default in BIOS. I am using reference GTX 980 and the difference is over 200MHz in Core Clock of the card
Well, both my cards are aftermarket one I believe:
GTX 1070Ti:
https://www.evga.com/products/product.aspx?pn=08G-P4-5671-KRGTX 1060 6GB:
http://www.gainward.com/main/vgapro.php?id=990&lang=enBoth needs something else then DSTM miner to trigger Boost or additional OC of the core.
I really wonder if I had this problem with EWBF. If not, than it is possible for miner to trigger the correct mode to get full speed. Would be nice if DSTM could look into this.
One of my rigs has reference 1080s in it. went and checked, their all running with 3d capabilities right now, i did nothing to the cards. are you running 5.7 or 5.6?