So I got an old Mac pro 2009 for free, but it was missing ram, a hard drive, and a GPU. So I bought some ram that fit the specification on Apple's website (see pictures) and then I bought a used MSI rx580 armor 8gb oc. (I've tested it in a windows system, it works perfectly) I also bought a 6 pin to 8 pin power adapter off Amazon. I put that all together and... Black screen. I hear the Mac bootup chime coming from the internal speaker, but nothing on display. I fear that it has something to do with the GPU or maybe even the power cable since I have noticed some people talking about using a dual 6 pin to 8 pin adapter for their rx580. Anybody got any ideas?