I'm about to do a mod on an Asus GTX 580 DirectCU II card - basically I'm going to remove the cover/shroud + fans and mount two custom fans on the heatsink.

Pictures of the card without shroud/cover and exposed heatsink here: http://www.bit-tech.net/hardware/graphi ... ectcu-ii/2

The heatsink is about 103-104mm wide, and I'm wondering if 92mm fans og 120mm fans are the better choice. The 120mm has the best CFM / noise ratio, but will cover more than the area of the heatsink and (probably?) increase the size of the dead zone. 92mm will be fully effective but leave 11-12mm uncovered.

Which would be the better choice? Any input is appreciated

I would probably go with 120mm, there are more options of fans out there than on 92mm. They should also give your better airflow at lower rpm, but depends on the fans.

Just wondering how are you going to mount the fans? are you going to mount them in another pci slot with a custom bracket?

Are you going PWM fans or just 3pin?

I was planning for a rather amateurish approach

1) Removing shroud + fans, thus exposing the heatsink
2) Mount fans using silicone and plastic-strips/steel wire or similar - whatever will fit

Eventually I might opt to go with a Prolimatech MK-13, depending on my success.

Hi, I'm really not sure which size fan to recommend, 92mm more "focused" flow for given noise but 120mm give more overall flow, and "over-spill" around the heatsinks that may benefit other components on the PCB.
I would definitely go with 4 pin PWM fans, as that's what it has currently, then the card can keep control of the speed. Where the GTX580 is quite tame idle and seriously hot under load I think speed controlled fan is the way to go.
You can see my thoughts and fan mounting and someone's efforts with an MSI GTX570 and 92mm fans in this thread.
Regards, Seb

Wouldn't it make more sense to install something like the
Accelero TWIN TURBO II then a rigged up ghetto cooler. You spent near $300 for the card but won't pay for quality VGA cooler? TWIN TURBO II is 2 quiet 120mm fans on it and there cheap over all.

I believe the Twin Turbo II isn't rated for anything higher than GTX560 Ti so I wouldn't recommend it for a GTX580. Also it has 92mm fans, well at least the one in it's box here does

I would sugest the Accelero Xtreme Plus II instead. It's rated for the GTX580, is much larger and has 3 92mm PWM fans on it. Should be an easy fit and forget job, but here in UK is ~£50, but for a £350+ video card you can argue the case for it. On other hand a pair of F9 PWMs from eBay and a few zip ties is ~£10 so not much lost if don't do the job.
Regards, Seb

It has nothing to do with whether I'm willing to pay for the cooler - the directcuii isnt a reference PCB, which means there's no guarantee that the accelero cooler (Xtreme Plus II) will fit on a custom PCB and to my knowledge there's no way of knowing prior to buying the cooler and stripping the card.

Do you happen to know of any installations of the Xtreme Plus II on the Asus?

Like I mentioned above, it's mostly a matter of the custom PCB of the GTX580 - the accelero might not fit. And while I don't mind at all paying the £50, I would hate to order it and find out it doesn't fit. Like I asked the poster above, if you know of any successful installations of the accelero on the asus gtx directcuii custom pcb, I'd be grateful if you'd share

I'm also considering trying out a used MK-13 to see if that will fit, but I'd have to find one first

Hi fuzzyboy, I’ve had a quick search of Google and didn’t find image or definite result in forums etc.
I’ve compared the image of the PCB from Bit Tech with images of stock GTX580 PCB and the fundamental position of GPU etc looks very similar.
I’ve looked at the Accelero Xtreme II’s webpage and noted the comment;
“The cooler is NOT compatible with any NVIDIA graphic cards with double deck DVI outputs.”

However this version II has a cut out to clear double height connectors at the bottom of the PCB, like your card has. The Height Restriction Drawing suggests need 50mm between the mounting hole and the DVI cover. Counting pixels on the PCB image I concluded you have 49.5mm!
That’s rather tight, if it really is 0.5mm it would probably bend/give that much. I think I’ve read of people with AMD cards removing the DVI cover to gain the few mm to fit Accelero coolers. The rear of the card doesn’t look like it would present any problems. As you have the card you maybe able to measure it more accurately and compare with the restriction drawing.

Or look in to the Thermalright Shaman as an alternate cooler, if the 8 heatpipe 140mm fanned monster will fit your case! Or just get a couple fans and see how it goes!

Good luck, Seb