  We present a full off-shell NLO QCD calculation of $pp \rightarrow e^+ \nu_e
b \mu^- \bar{\nu}_\mu \bar{b} b \bar{b} + X$. Results are obtained using the
HELAC-NLO Monte Carlo framework. We discuss a comparison to previous results
and to experimental measurements. We also investigate the contribution of the
initial states involving $b$-quarks and we introduce two $b$-jet tagging
schemes.
