Question Legacy/CSM boot on Asrock X570 Phantom Gaming 4/4s


Feb 18, 2019
Hi :)

I'm currently considering the purchase of a motherboard with 8 sATA3 ports.
The cheapest options in my region are from Asrock:
- Asrock X570 Phantom Gaming 4
- Asrock X570 Phantom Gaming 4s

However, I need the system to boot in legacy/CSM mode. UEFI won't work.
It seems like some users are reporting that their Asrock X570 Phatom Gaming 4/4s cannot enable CSM anymore after a BIOS upgrade.
Can anyone confirm that CSM is still present in the latest BIOS versions?
How could I check that (other than by contacting Asrock via a support ticket)?

Thank you very much in advance for your help.


IMHO, the best route would be to go for a platform from the yesteryears like the one's from Intel during Skylake or Kabylake, since they are known to have CSM functionality on them. You will also need to understand that the standards for BIOS are now gravitating towards UEFI only, meaning CSM can and will be phased out. I suggested older platforms since they will have their CSM functionality intact. AMD's Ryzen platforms are all seeing BIOS updates to the latest version and if CSM is mission critical for you, I'd advise on not investing on AMD's Ryzen platform.

To all add more food for thought, CSM is possible to have on all platforms, the real question is whether the devices you need to run in CSM are compatible with the platform. We've all seen how dropping a UEFI VBIOS GPU on a non UEFI BIOS motherboard(and most prebuilts) ended up with a black screen in spite of having the PSU check out and the audio proved that the OS did boot to GUI.

So yeah, contact ASRock and let them know what you're looking for. I've had to contact them in the past for processor support on a particular motherboard while on an older BIOS version.