Great information,
thank you 
I started my mining career with just my solo MSI GTX 1070 on my home rig, but am looking at making a dedicated miner.
Been building my own computers since way back but never made a miner, and my question is about the PCIe slots/speed -
Got an older MSI K9A2 CF V2 motherboard I may use to start? (It runs now with 4gb ram and Athlon duo core 3.0/ Win 7 - was retired but mining got me to fire it up to test it. - not my current system)
https://www.cnet.com/products/msi-k9a2-cf-f-v2-motherboard-atx-socket-am2-plus-amd-790x/specs/ The card it has is too old - HD 5770 radeon and is a PCIe 2.0
By looking this post over it appears one can run newer PCIe 3.0 cards on these older boards? i.e. the Dell T5500 - Just trying to wrap up my confusion on how PCIe 1/2/3.0 slots make any difference to mining. I'm used to building pc's for..
eh computing/internet/gaming/etc.
If attaching by risers/cables - it makes no difference as to the cards requirements for a slot? So if anyone can enlighten me / point me to a good guide, I would be most grateful.
Happy mining!
EDIT:
found some info on this, sorry have waaay to many thing s going on here atm.

But any comments to this are welcome, in case anyone has ? about this as well - here is a post I found:
http://www.gobitgo.com/articles/1001/How-To-Correctly-Use-and-Install-PCI-E-Riser-Cables/