I just got a new iMac at work (I'm a PC/linux guy, but my boss is a Mac guy). It has a ATI 6970, which is one of the best video cards for bitcoin mining today. So I figure I'll download Diablo miner and set it up to run with default settings. Apparently Open CL doesn't work very well on a Mac, so I was only mining at about 1/4 the rate that the 6970 would get in a PC, but still figured it would be worth it to run it over the weekend.

So I come back on Monday, and the computer is froze. I restart, and I'm getting visual artifacts on the screen, and it freezes, usually at the login screen, sometimes it logs in, only to have more video artifacts, and freezes shortly after. I'm pretty sure I fried the video card. I'm assuming that the iMac must have really bad cooling on the video card, and it overheated. Aren't there any safety features to shut down the computer if the hardware is getting dangerously hot?

I load in safe mode, and delete everything related to bitcoin or the diablo miner, and call the company's tech guy complaining my New iMac is acting up, acting like I have no idea why it would do that.

I'm thinking of building a mining machine, and am trying to figure out if it will be profitable. I've used this: http://lorelei.kaverit.org/cgi/calc.py to calculate the profitability based on today's difficulty and compared with today's BTC/USD rate. But I would really like to see how the [BTC/USD rate]/[difficulty] has changed over time so I can try to guess at future profitability. I can find graphs for each (difficulty here: http://bitcoin.sipa.be/ and BTC/USD charts from MtGox), but not the raw numbers. I need to find the raw numbers so I can compare them and make a value/difficulty graph.

Does anyone know where I can get the raw data for difficulty and exchange rate? (or better yet, a graph of the ratio that someone has already put together)

Thanks