Review on Tech 1067MHz 1066MHz MacPro4 Memory by Brent Dietrich

I bought these for my mid 2010 Mac Pro with El Capitan which was upgraded from the factory 4 x 2GB RAM. Installation is easy, but I tried being greedy and using the factory RAM in the remaining slots. A white flashing light when starting says "No". It's easy enough to take them out and just run the new 4 x 8GB (slots 1,2,5,6) and it runs like clockwork. Great price for a decent increase in performance.