video cards dont mine bitcoin. I suggest doing more research before you order your first part.

I've got a few video cards laying around and wanted to try to put together a mining rig for bitcoin.  This would be a first for me, I've always just bought Bitmain miners, but why not if I've got most of the equipment and can afford a few hundred to try.
I see that MSI has a Z370-A Pro is only $100 after $10 MIR that's designed for mining.
The only other thing I would need is a CPU, but have no idea which one is recommended or if a minimum is required.  I know the graphics card does the load, but if I've got 8 cards running (2 on motherboard and 6 on riser cards), do I need an adequate CPU to handle the load?  With the Z370 it needs to be a 8th gen. Intel.  Will a i5 8400 65W be OK, it's $200?
I've got the rest of the big items.  A couple 8GB sticks of DDR4 (should I use both or just one)? A CPU Cooler. A few Hard Drives lying around.
I've got a EVGA 1600w Platinum power supply that i'm not using. (will this handle 8 GPU cards?)
I see a case is $60 on eBay https://www.ebay.com/i/322581889838?chn=ps&dispctrl=1 if I need to go with one.
And the riser card set for 6 is like around $45 and the USB 3.0 card is $30 on amazon.com are the accessories I'd need.