I'm pretty new to this whole deal. My friend got my started on it today. Essentially my issue is that I'm running 2 4890's and they over heat after running GUIMiner for about 20 minutes. I've ramped up the fan speed to no avail. They still over heat and the system crashes. I'm assuming this isn't normal seeing as how some people run systems 24/7 and successfully make a little money. I've never had any issues with these cards over heating what so ever in any other circumstances. I am running them in CrossFire, but it seems to be the only way to get it to use both cards. If it isn't running in CrossFire, then it will only work at the speed of having just one card running.  Even with just running on one card, it still over heats the card. Any suggestions? I'd really like this deal to pay for a new set of video cards. lol