This message was posted by Intel Corporation on behalf of
Thank you for contacting Intel Customer Support.
We regret to inform that the Intel Server Board S5520HC is currently in End of Interactive Support (EOIS). This means that Intel no longer provides interactive support for this service via telephone, e-mail, chat, or other tools. Technical articles will continue to be available on the Intel Support website.
Definitely, somehow the system has been losing power. I would like to recommend to use PSUs that were validated with the server board.
Please check this documentation: