Dear Matteo Thank you for your e-mail. I used the MKL 5.2 and MKL 6.0 (for Paolo: Firstly I got the beta version of mkl6.0, but recently I got whe full MKL6.0 without restrictions). But I found that PWscf compiled with ATLAS works fastly than with MKL. May be, the version 5.1 is better than 6.0 ( I don't know). Sergey