RAID controller overheats in certain cases

Install active fan. It’s $2 :) Alternatively you can go software RAID and XOR checksums will heat your CPU rather than RAID card FPGA or ASIC.

From Adaptec specifications sheet:

Operating temperature: 0 °C to 55 °C (with 200 LFM airflow). Note: This adapter contains a powerful RAID processor that requires adequate airflow to operate reliably. Only install this card into server or PC chassis with at least 200 LFM airflow. Temperature measured 1 inch from RAID adapter.

Maybe your first case/server has poor airflow on the PCI-E slots zone, or something heats up the air around the card.

As suggested, you should solve attaching a small fan to the heatspreader.