Obviously this depending on your trading style. I am using a laptop and faced no problem with 4 pairs on H4 with a couple of indicators.
I do agree that you will need a desktop workstation with multiple screens if you are working with multiple pairs and each pair has quite a few indicators power up the screen like a carnival.
I do agree that you will need a desktop workstation with multiple screens if you are working with multiple pairs and each pair has quite a few indicators power up the screen like a carnival.