user13699: I have a GTX660 right now, but I bought an R9 290x recently. I was wondering if I can leave both in my pc and use one (the GTX660) for Bitcoin mining and one (the R9 290x) for everything else (mostly games).  

Is this even possible?  
Will it decrease gaming performance to run a miner on a separate card?  

The rest of my specs:
i7 3820 @ 3.60 GHz
16GB DDR3 RAM @ 1333MHz
Asus 2011 P9X79 Pro
Windows 8 pro  
I bought the new card for gaming, but if it would be possible to do this with my old card without losing performance that would be great.

user13703: I'm pretty sure both cards have to be the same make and model for your motherboard to recognize them so that both would work at the same time.

user14784: Yes you can 
I use a gtx 460 (as the main card)
and r9 280x as alt coin mining card. (bitcoins... ha ha impossible)
Just install amd drivers for the mining card, and use a dummy plug with the r9. 
also some cgminer special commands are needed in order to make it work nicely..try googling a lot until you find the answer for the cgminer command line... can't remember at the moment

user13700: With the advent of ASICs, Bitcoin GPU mining is no longer profitable. I would recommend mining a Scrypt coin such as Dogecoin or Litecoin. (You can then trade it in for Bitcoin on an exchange, if you prefer.)
To answer your original question, yes, you can use one card for mining and the other for actually running the computer.

13699: <p>I have a GTX660 right now, but I bought an R9 290x recently. I was wondering if I can leave both in my pc and use one (the GTX660) for Bitcoin mining and one (the R9 290x) for everything else (mostly games).  </p>

<ol>
<li>Is this even possible?  </li>
<li>Will it decrease gaming performance to run a miner on a separate card?  </li>
</ol>

<p>The rest of my specs:<br>
i7 3820 @ 3.60 GHz<br>
16GB DDR3 RAM @ 1333MHz<br>
Asus 2011 P9X79 Pro<br>
Windows 8 pro  </p>

<p>I bought the new card for gaming, but if it would be possible to do this with my old card without losing performance that would be great.</p>
 13703: <p>I'm pretty sure both cards have to be the same make and model for your motherboard to recognize them so that both would work at the same time.</p>
 14784: <p>Yes you can </p>

<p>I use a gtx 460 (as the main card)
and r9 280x as alt coin mining card. (bitcoins... ha ha impossible)</p>

<p>Just install amd drivers for the mining card, and use a dummy plug with the r9. </p>

<p>also some cgminer special commands are needed in order to make it work nicely..try googling a lot until you find the answer for the cgminer command line... can't remember at the moment</p>
 13700: <p>With the advent of ASICs, Bitcoin GPU mining is no longer profitable. I would recommend mining a Scrypt coin such as Dogecoin or Litecoin. (You can then trade it in for Bitcoin on an exchange, if you prefer.)</p>

<p>To answer your original question, yes, you can use one card for mining and the other for actually running the computer.</p>
