I just installed this cooler yesterday
Not the easiest to install i must admit. No real instructions on site or included, so I had to read between the lines quite a bit.
But, after a nerve wracking 1/2 hour in which the heat sinks from the memory tried to fall off, i had it all connected ( plus the dual power connections for the fan itself ! ) and put it to a temp test.
I tested the card on stock cooling, automatic setting with fur benchmark on 1280x1024 x16 anti aliasing for stability test 30 minutes
temp was 93
idle before that it was 79
when setting the fan to 50% temps dropped to 85 during stress and 75 idle
AFTER installing the twin turbo, idle temps dropped to 48c !! yes , a 31 degree drop.
during stress i hit 55-60 TOPS , and thats when i really stress it ( 100% stress for 10+ minutes )
this thing dropped 30c off my card like nothing.
Its not much bigger than the stock cooler either, so it fit my case pretty snugly.
All in all, i highly recommend this cheap but usefull fan for any 4870 user.
FYI, I have the sapphire vanilla 4870.
Just a small addition to my earlier review.
A few days ago my computer started glitching during games, and even shutting down during stress tests.
Apparently one of the memory heat sinks fell off the card.
The glue there is mediocre at best, and installation of the 2 heat sinks on 3 memory modules is risky.
Anywho, after applying a nice layer of thermal sticky paste , i reapplied and the card is working well again.
So to restate, the heat sinks do NOT connect well. make sure you have thermal pads or sticky thermal paste to stick it on there.
Did you clean the chips with Artic Clean or some other final cleaner before sticking the HS on? I have seen it before. Even with alcohol there is still some of the oil based stuff in the thermal pad left and you can't see or feel it.