whoa, 70°C is way too much. Even now with the warm weather my 3850 is at "only" 50 °C.
So this is definitely not a driver problem imo.
At first you should check the fan and the heat sink and clear it off from all the dust. I recommend to do this every quarter of a year. Dust is known to destroy fans. So take the test. Remove the card and spin the fan a bit. It should spin w/o problems for some seconds. Ah well b4 I forget it.
Very important: If you use a vacuum cleaner to remove the dust from fans be sure you jammed them because of the dynamo effect.
Another thing about monitoring the temps and stuff.
I suggest ati tray tools ( I never install ccc it's crap imho
). there you can f.e. setup a systray icon where you can monitor the temperature easily. Within this great tool there's also a monitoring display with graphs in which you can setup all kinds of sources from Clockrate (in Mhz) to GPU-Activity (in %).
if nothing had changed after removing the dust... and the fan spins fine for some seconds...
you should check the heat-transfer paste on the GPU. My guess is that it melted away. If so remove any leavings of the paste and put on some new one. You can buy it in every good computershop for under 5€.
Ofc, you have to remove the fan-cooling-system first which can be tricky if you do it the first time. Be careful when doing so and don't simply rip it off of by force. My old 3650 had lots of screws and @ the beginning it was a bit of pain in the ass to remove this thing.
If you have some bad luck and the fan is broken (also happend with my old 3650)... there are cooling kits for graphic cards out there for something around 20 €. But that should be last solution if nothing else works.
As I said b4, i don't think it's a driver problem. This doesn't make any sense. You should get over 70°C with a full load of 100% and not with 1 to 10%... so check the cooling system of your card b4 you waste your time with other things that don't make any sense regarding this problem
gl and if you have some problems doing the things I mentioned feel free to write me a pm as I don't check in here every day.
Greetz Krazee
ah well I re-read your post and seen the thing with recalibrating the fan speed. Now I remembered that there were cards with this specific problem (yea always happens after I wrote all this stuff above
) - besides all that removing dust and checking the fan, etc... still is important...
In att (ati tray tools) you can setup fan speeds for every temperature you like. Also you can setup to run the fan always at a specific percentage.
Either way b4 I would waste my money on a new card I'll check out this "little" tool if I were you. It has so much to offer. I could write pages about it's "pros"
edit: besides the fan speeds you can also change the PCI-Latency in att. Try a value of 64