DDR3 (Double Data Rate) 665 MHz = 1330 MHz. The frequency will be the same. It's best to use identical modules, but 1333 MHz modules usually run at the lowest common timings.
DDR3 (Double Data Rate) 665 MHz = 1330 MHz. The frequency will be the same. It's best to use identical modules, but 1333 MHz modules usually run at the lowest common timings.