CSM (Compatibility Support Module)
Also searched as: csm · compatibility support module · legacy boot
What it means
A BIOS option that lets modern firmware boot in an old-fashioned legacy mode for older operating systems and hardware. On a current gaming PC you generally want it off.
More detail
It matters because Secure Boot and some anti-cheats need CSM disabled to work, and flipping it on a Windows install set up the other way can stop the PC booting. If you change it, know that you may need to adjust how the drive boots too. …
In the Blackbook
The deeper explanation continues inside the app. The Blackbook publishes its verdicts here — the full write-ups stay in the book, on your rig, next to your own measurements.
The Compy Blackbook holds 191 graded entries like this one, judged against your hardware — and every change it does make is reversible, with the receipt to prove it.
See Compy →