3dfx Voodoo3 AGP
Perhaps a RAM test board. It has 'Siemens' RAM which is not common on 3dfx cards. Notice the Avenger chip (or actually not), it's removed. It also lacks a FET.
The board has an engineering sample attached which says 'locks instantly in Quake 3'. The RAM test probably failed somehow on which someone decided to remove the Avenger chip .