Mines bitcoins at 70-75 gigahashes per second without being overclocked.

If it doesn't show up in Device Manager, then it's probably not related to a dummy plug. The card should show up in device manager as "working properly", but Windows will consider it "disabled" until it senses a monitor attached.

Try replacing your main video card with this one to see if the card is bad or something else. You could have a bad card, a bad driver (try reinstalling the drivers), or a bad motherboard (or the slot is somehow disabled).

More exclamation points please. !!!1!!!!!

Anyway, the DVI to VGA adapter by itself won't help. That's just a few wires connecting the VGA pins to the appropriate DVI pins.

What you need is to fool the computer into thinking a monitor is attached. you can use another monitor, or a KVM switch, or a dummy plug.

Make your own dummy plug like this: http://blog.zorinaq.com/?e=11

read more in this forum thread: https://forum.bitcoin.org/index.php?topic=16816.0

I'm just putting this out there because I'd like to see it make coins for my own non-profit org.

How about making a bitcoin miner that runs when the screen saver is active (see http://en.wikipedia.org/wiki/List_of_distributed_computing_projects).

It could have a cool graphic that shows progress or lists some of the hashes it has generated and other stats.

There would be an option to use a GPU or CPU and it would be nice to the computer, i.e. not running at 100%.

It would go into a pool which would be customizable (send worker shares to account X on pool Y) - perhaps with a small portion going to the publisher (with full disclosure of course).

Anyway, just throwing that out there. I think it's a neat idea and would look really cool on all our screens at work.

I just signed up and brought the total to within a cat's whisker of 100 GH/s.

Using the 6990 is great to concentrate megahashes per slot on the motherboard. But at over $1.00 USD per MH, it can cost twice as much on a per MH basis than other cards. If you are not looking to stuff a single motherboard with as much power as possible, using a few 5830's or 6870's gives you more bang for the buck.

I have a place you can run it in LA if you are willing to share what it mines. I'm not sure at this point if it's worth it to buy a mining rig or just buy BTC on the market.