The string is not a specific model name but rather a regulatory or industry specification marking found on a wide range of older Intel desktop boards . Because these markings are common across various models, boards labeled with them can have different chipsets, sockets, and capabilities. Understanding the "21 B6 E1 E2" Marking
(Generous score based on reliability; would be a 1/10 based on performance). intel desktop board 21 b6 e1 e2 specification
Do you have a specific Intel motherboard model number (found on the PCIe slot)? Drop it in the comments for exact CPU and RAM compatibility lists. The string is not a specific model name