when i ran the app it stopped midway. how do i get it to reanalise my gpu? 

AHowes
I never got that to work.. so I figure it's buggy and and broken. I use 3dmsrk to see if my. Overclock is stable.. climb a little at a time and test.

Same here. 3DMark Extreme for dx11 and Time spy for Dx12. When satisfied I run the stability test which runs the first graphics test 20x without any pause. Frame rate consistency above 97% is considered stable by Futuremark. I always aim for 98.5% or more. Often had 99.4%, but never 100%. I am giving detail because I have the paid version (non-steam) and not totally sure if the stability test is included in the free version? It's worth paying for the upgrade IMO, I did it years ago, it lasts for life, and checks for updates (manually too)
The new extreme Time Spy is an absolute CPU killer. On my i5 3570k @ 4.75GHz, the last bit runs, literally not more than 2 frames per sec. Laughable. It does OK on the standard free Time Spy though. Will be interesting to see how the 6+6 i7 8700k handles that bit. I am planning to upgrade early next year.
 
Finally just to say that the endurance test (Both Firestrike x 20 and Time Spy x 20) if both passed you can be confident that the GPU is stable at said speed. Very useful, and not dangerously stressful for the card, unlike the old furmark before it was locked.