Overall not much is gained in power efficiency. Same 40nm TSMC manufacturing process, a bit smaller die, expected result. Idle clocks for both new cards 100MHz core and 300MHz memory and idle consumption on par with 5770.
What do you mean "not much gained"? The power consumption of the 6850 is nearly identical to that of the 5770 while the performance is closer to that of the 5850. Finally a worthy candidate for a fanless 4850 replacement.
The TDP is reference design TDP values from AMD.
Different non-reference board designs from vendors may lead to slight variations in actual TDP.
Card Load Idle GFLOPS
5670 64W 15W 620
5750 86W 16W 1008
5770 108W 18W 1360
6670 63W 8W 1152
6850 127W 15W 1488
6870 151W 19W 2016
Not much gained as in going from the 5770 which no ODM sells as a fanless card in the US the 6850 has a higher TDP. For those of us in the US or those in hot environments or any risk adverse buyer we want a card under 100W TDP, preferably right near the 75W line so a fanless "green" version can be made with higher quality components and be run without the PEG power connector from the PSU. That leaves us ignoring the new 6xxx cards right now and still focusing on the 5750.
Now if the Wikipedia article is correct it looks like the 6670 will be faster than the 5750 though if that is the case I wonder why it doesn't have a 67xx name. Whatever they decide to call it if it has the performance of a 5750 with the power draw of a 5670 as suggested by those numbers it will be the ultimate performance/power quiet video card.
I'll paste in a quote from another thread to support the fanless 5770 isn't available line of thought
First off I can't buy that card in the US. A google price search including the terms "Gigabyte Radeon HD 5770 Silent Cell" doesn't show it on any site that doesn't list the price in Euros.
If I search for the part number I get 3 US sites that don't have it in stock all of which call it "HD 5770 1GB Silent RTL" whatever RTL stands for (one of which shows a picture of a card with fan) so I'm not sure I'm getting a valid search by part number.
Second you do have to admit they really push the boundaries on that card
* replaced two DVI connectors with one DUAL link DVI connector
* Heatsink protrudes into space where the 2nd DVI connector normally would be
* Heatsink protrudes vertically keeping this card out of some smaller cases due to height.
* Heatsink protrudes length wise keeping this card out of some smaller cases due to length.
In fact in all the searches I've done I still haven't found the measurements of this card. The Gigabyte support download center doesn't have a manual for that card yet. And the specifications page has no physical dimensions.
I give up. It's a interesting paper launch or maybe an interesting Euro only option but I can't find it and I've been searching way too long.
the next reply in that thread mentioned the 5770 silent cell doesn't fit in an Antec Solo.newegg 5xxx fanless