SOLVED Help with GPU throttling

I have read through some posts and tried a few things to no avail. I am trying to max out my GPU as far as it can on the stock Twin Frozr II cooling setup with MSI Afterburner and using Furmark as my test program.(MSI Kombuster "seems to" not test as hard) My temps stay under 70c @ 995/2150 but get throttling once and a while. Select Physx processor is set to auto select, verticle sync is set to use application setting, and I believe I have enough power to run it. All case lights and extras are disabled but I am running and overclocked cpu @ 4.2 GHz and triple channel mushkin 1600 @ 1.64 v. Also 2 Scythe Kaze Master 300 cfm fans on my rad. PSU is an OCZ zx 850w 80 plus gold. I have backed of of my settings, and still happens once and a while. Games, I don't know don't play many just more interested in pushing my components to their limits for benching and eventually will upgrade my gpu cooling to water which I should have done first anyway. Any suggestions or help??Thanks guys

EDIT: I don't care about stability too much since I just need to get through heaven and other associated HWBot benches and set my marks.Stability will come later after I get a new card or kill this one first. Driver version 301.24

Ok then........

How do you know its throttling? It shuldnt be at those temps.

When i run Furmark it tells me it is throttling and drops down to about 12 to 16 fps. Before it even hits 70c. I was wondering if maybe my psu wasn't strong enough but it only does it once and a while. Is my gddr too high maybe? Just to add, I keep everything clean. I take apart the psu and clean the heatsinks and all of my case and fans etc. once a week. Thanks Earthdog. By the way I see you creeping up on me in FAH stats!

Stop using furmark. The card will throttle. Loop heaven or 3d11

I got it. I have entered some decent scores on the bot lately due to your advice. Thanks worked great Earthdog!