Hi, First post, but Im a long time lurker. Anyways, I have an issue with my Mac Pro (2,1) with random shutdowns, and a solid red light under "A2". I tried swapping the positions of the sticks and the same red light comes on. I also moved the top riser to the bottom, and same light is lit. This issue with the red light occur when I was using old existing ram. Recently, I replaced all ram sticks with OWC and the same solid red light is on under "A2". In system profiler, it says I have 24GB ram and all slots says "OK" Is my riser dead or is it another issue? Specs: Mac Pro (2,1) 3GHZ Dual Quad Xeon El Capitan Radeon 7950 24GB ram Any help will be much appreciated, thanks.