Follow up question: when mining with two cards on one computer

Is it possible to mine eth on my 8g and rvn on my 4g?

I just bought my pci e riser and I have watched a few videos on how to set it up. Has anyone had any experience setting it up so that both cards sit in your tower? All the videos I have watched have set it up externally. Is this due to heat reasons? Or just tower space?

Thank you all again in advance. If you have images or YouTube links that would be amazing. Thank you.