This is one of the most difficult questions to answer because there are so many variables -- The major one being I've never played EVE so I don't really know the load it requires to run. However, the easiest thing to do would be to check out this page on the ISBoxer Wiki. I know that the link takes to a section that talks about bottlenecks and that you don't currently have a bottleneck, but the Open Hardware Monitor program it has you download is a good place to start for monitoring what your hardware is currently doing.

So, fire up your accounts and fire up OHM and then see what it reports. You're looking to increase the size of your fleet by over 50%, so when you look at the program... Do you have > 50% of your system available to run that many more accounts? My guess is going to be no since Shadowandlight over on the ISBoxer forum runs somewhere around 25 accounts and he uses either a 3930K or 4930K.