It's a stock Mac Pro setup, so that'd be fresh!  I don't even know if they have the temp sensors on the GPUs inside these rigs. 

If so, should Hardware Monitor or iStat be able to read the temps from inside Mac OSX?

I assume you are trying to setup a local server? The error message says that the username is entirely missing. Try reconfiguring by pressing Y + Enter during the first seconds of the application startup. When connecting to a local rpcserver, the username and password you set in the client must obviously match.

Missing argument for option: u

usage: DiabloMiner -u myuser -p mypassword [args]
                  
 -D,--devices    devices to enable
 -d,--debug            enable debug output
 -dd,--edebug          enable extra debug output
 -f,--fps        target execution timing
 -g,--getwork    seconds between getwork refresh
 -h,--help             this help
 -l,--url        bitcoin host url
 -o,--host       bitcoin host IP
 -p,--pass       bitcoin host password
 -r,--port       bitcoin host port
 -u,--user       bitcoin host username
 -v,--vectors    vector size in kernel (1 - 6)
 -w,--worksize   override worksize
 -x,--proxy      optional proxy settings IP:PORT<:username:password>
 -z,--loops      kernel loops (PoT exp, 0 is off)

Remember to set rpcuser and rpcpassword in your ~/.bitcoin/bitcoin.conf
before starting bitcoind or bitcoin --daemon
logout

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