When I first built my rig (see Sig), the budget only let me get one graphics card (and not the top of the line kind), so I went with the ZOTAC ZT 50401-10L. Great card for the price IMO, so when newegg had it for $105 a week or so ago PLUS a $30 MIR, I jumped on it. Set up SLI, everything performance wise was great. Except...
My Motherboard only supports SLI on the Top 2 PCIe Slots (having trouble addind images, link to flickr below) which makes the 2 video cards touch (as in make physical contact). After an hour of gaming I checked the GPU temps. Bottom card was around 60 degrees Celsius, but the top card checked in at a whopping 91 degrees C (approx 196 degrees F). I pulled an 80mm Antec fan that's probably AT LEAST 10 years old from an ancient rig just to test a theory.
I zip-tied the fan to blow as much as possible through the top (and bottom, but priority is top), and GPU-z reported it dropped to 84-85 degrees C under load (I left the system OFF for about an hour to cool between tests)
Given the results, I was going to buy an 80mm fan and attach it in a less jerry rigged fashion, as well as add another 2 case fans to have the most airflow possible... I was wondering if anoyone had similar problems and came up with a different solution (or tried my idea and had it work terrifically/fail horribly).
There are a couple of places to put a fan to help with cooling. You can put one in the side panel in a spot so as to blow directly onto the two cards. If there is no precut hole for a fan then you can make one , the side panel of the case is pretty thin metal and cuts very easy. If you have a window then you can cut that as well , it just takes patience and being careful. If you have a Dremmel tool then it becomes even easier.
The other place is attached to the hard drive rack so as to blow towards the back of the case and aimed at the end of the cards.
Not to say that you shouldn't be careful with heat issues but a video card can get hotter than a cpu and it has a higher thermal shutdown. A cpu will shutdown at around 90c while a gpu can go as high as 115c. Like you I don't think I would chance it much over 90c and would take the card out as well to wait for the fan.