Hardware requirements for nodes (RPC, validator, ...) should be generally along the lines of the specs outlined below.
For specific node use cases (e.g. full history) specs may differ (and grow) over time.
CPU: 6+ cores
Memory: 16GB+ (32GB advised)
Disk IO: 10k random RW
Disk size: 100GB+
Filesystem: EXT4/XFS/...
Network IO: 100Mbit+
CPU
16 cores
20+ cores
40+ cores
Memory
32GB
64GB
128GB+
Disk IO
15k random RW
20k random RW
30k random RW
Disk Size
500GB
1TB
2TB
Filesystem
XFS
XFS
XFS
Network IO
500Mbit+
1Gbit
10Gbit