RAID adapter unrecoverable error SDRAM connection

Hello,

I have this error on a PE 1950:
"RAID adapter
Unrecoverable error!!!
Please check the SDRAM connection.
If problems persist contact Tech Support.
Press any key to continue."

The HDDs are unavailable. I tried: booting offline Linux, disable RAID controller in BIOS, enable SATA in BIOS, BIOS update to 2.7.0. Nothing worked... :emotion-6:

Do you know what should I do? Is the RAID controller dead?

Regards,
Sergiu.