SPCR

I have a p183 and a HD6850 an I plan to replace the cooler with an Accelero S3.

Now I'm wondering. Should I attach a fan directly to the heatsink or would it be sufficient to mount a fan like this (the only barely visible at the far right):

http://www.silentpcreview.com/files/ima ... nity3a.jpg

I will need the latter as an intake no matter what, but it would be nice if it could work both as intake and to cool the card. This fan would probably run faster than the other fans to create positive pressure.

Thanks!
fokfokfok

It is not possible to predict the result. You just need to experiment bot ways. My guess is that you will get better cooling with the fan up close to the fins... and better sound with a larger case fan standing back a bit. But that is nothing more than an educated guess. Aircurrents and cooling are just to complicated and spooky to try to predict.

I've used a similar setup to cool a HD5770. Temps would most certainly be better with a fan directly on the heatsink, but otherwise that intake fan provides enough air to keep the cards at safe temps. In my setup, the max GPU temp was ~84c in Furmark with all three system fans going at 500RPM and the P182's door closed. Using the same 500RPM fan speed and with the door still closed, in Crysis it was more like ~60-65c max. The 5770 has a 108W TDP, while the 6850 has a 127W TDP.

Not exactly sure how that would translate to a 6850 in a P183, but the above data should give you an idea of a worst case scenario. The bottom line is that you'll get safe temps. With the same 500RPM intake fan speed and with the P183's door closed, I'd guesstimate perhaps ~70-75c max in games, and ~90-100c max in Furmark (the latter of which isn't really relevant).

I'd actually try to remove the free-floating fan completely. Without it, the back vents should provide a direct fresh air intake for the graphics card.

Modo wrote:I'd actually try to remove the free-floating fan completely. Without it, the back vents should provide a direct fresh air intake for the graphics card.

I've tried that with my setup. Temps rise significantly, even with the bottom expansion slot covers removed altogether. Then again it may just be because the GPU heatsink is so far forward on the Asus CuCore 5770.

Nonetheless, with this setup IMO it's best to have fresh air blowing straight onto the GPU heatsink, instead of relying on the case's exhaust fan to pull air in through the PCI expansion slots. I imagine it would make an even bigger difference with the hotter HD6850.

Thanks I guess I just have to experiment.