Hey guys, I just got my 5850 yesterday (UPS guy ran late and I wasn't happy about that) mine is a Gigabyte variant. And another treat, I got my Accelero S1 also, which was a nice surprise.
So my first impressions of the card is that it is a heavy peice of technology.
I am not one to purchase "high-end" parts and the heft of the thing was nice. Popped it in and I threw a few games at it (Fallout, L4D, Empire Total War) and it handled them dutifully. A huge update compared to my faithful 4770 to be sure.
Room temp was ~21c . Open workbench. Stressed with ATI overdrive overclock utility and then Furmark
In terms of temperatures, the stock solution was certainly up to the task with temps in the high 40s under load and in the mid 30s idle. I discovered that it exhausts half of its heat out the back and half through side vents in the shroud into the case, so it does provide a "full sized" exhaust outlet. This was at 25% fan speed. However, even at lowest fan speed, it is a bearable hum but not up to SPCR standards. Just for fun I threw it up to 100% fanspeed and that hum turned into a roar, I'd say it was fairly impressive in terms of decibel output. Under load, I didn't see temps go above 41c which is great.
Now with aftermarket cooling, it faired quite well but I have yet to really test it heavily. The Accelero did have some fins bent by the dual DVI connectors to fit, but otherwise installation was easy. I have to immediately point out that a dedicated fan is a necessity from what I've seen as it just kept getting hotter. Even with very little airflow, however, dangerous temps were never achieved. A 500rpm 120mm Scythe managed around 51c under load and with a 1200rpm scythe the numbers were better than that of the stock cooler at 100% (~39c under load).
I am confident that the card runs cool enough to make for an stunningly good quiet gaming platform.
On a side note, I don't know about the cooling needs of the VRM chips as I could not target them for temp measurements. I got the S1 heatsinks to stick but not very well. And these chips might be of issue in a low airflow cooling environment. Luckily, it looks as if it is compatible with any of the VRM cooling products from the likes of Zalman and Thermalright. I'll order one eventually to see whether they will fit with or without modification.
Will update with more impressions and info when I get the time to test it more thoroughly. Spent time that my girlfriend will appreciate for sure
Many thanks to my Alissa for putting up with my computeryness.