Quote Originally Posted by SuicideCabbage View Post
... the 5830s are a 1GB card, in BOINC they are reporting 512MB ...
I had the same problem with my 2Gb HD6670 card, being recognised as a 512Mb one. It was the default Linux drivers, I installed FGLRX and switched to that to cure it.
What version of Ubuntu are you using, 16 by any chance? If so, you will find FGLRX isn't supported any more, you'll need to use 14 instead. I'm using Mint 17.3 on my Linux box with the HD6670 in it, because that is based on Ubuntu 14 and works. The latest version of Mint (18) is based on Ubuntu 16 and will have the same problem too. Do a Google/Bing/whatever search for FGLRX and Ubuntu 16 - there are a lot of unhappy graphics card users!