This is a question we get asked reasonably often – what is the right SAS cable length for a Norco 4220/4224 chassis while using IBM M1015 HBAs?
50cm: Doable but puts a great deal of strain on the connectors, particularly on the card end.
60cm: Enough with some slack and no excessive pressure on the connectors.
75cm: Enough with a reasonable amount of slack; will likely require a few cable ties to prevent obstructing airflow if you have more than one.
1m: Too much slack.
We tested the lengths with the HBAs in each of the available slots, from nearest to the CPU to farthest away. Were you to have raid cards/HBAs with end ports rather than upwardly-facing ports you would be able to get away with the 50cm cables without issue.