There are no minimum system requirements for the client terminal, so you should stick to recommended parameters:
Manual trading
CPU 2.0 GHz
RAM 4 Gb
Disk Space 600 Mb (installation plus history cache)
Windows 7 or higher
Microsoft .NET Framework 4.5 or higher
Automated trading
CPU 3.0 GHz
RAM 8 Gb
Disk Space 600 Mb (installation plus history cache)
Windows 7 or higher
Microsoft .NET Framework 4.5 or higher