The old stick is just 2GB and mixing sticks has been the cause of many hard to diagnose BSODs.
Besides it won't work as the new board takes DDR4 memory and the old is DDR3.
Best to leave the old ram, CPU on the old board and sell it as a set.
Post was last edited on May 10, 2019 1:07 PM PDT
That looks familiar. Might be the same card I used at https://www.cnet.com/forums/post/b662a1a0-11f1-4e59-9c40-9f9156c8ffab/
That old beast is still running great. I did push it farther than I should have with a step to the 1060 and the last best CPU I could locate for this old system. You can compare your test results with mine if you have time.