The motherboards has:
PCIe 1.0a x1
PCIe 1.0a x16
AGP 8x
three conventional PCI slots
Currently setup:
PCIe x1 = USB 3.0
PCIex16 - Adaptec RAID 6805T x8 card
AGP 8x = Nvidia GeForce 6600GT
PCI = Intel Pro 1000MT
I tried a GeForce 6800GT in the AGP slot, which is able to run my 1080p videos from my phone/digicam a bit better, but there is some screen tearing which occurs, like the screen gets all cut up into triangles. I'm not sure why. It happens after about 2 minutes of uptime in Ubuntu, but had no issues in WinXP. That's why I'm using the 6600GT. 1080p videos are almost perfectly smooth, but I suspect the PCIe bridge adapter on the board is causing some bottleneck. I have a non-GT 6800 I want to try, but it has taken FOREVER to get here from Russia.
I've tried the AMD 4350 and 4650, but they have this weird issue which causes horrible stuttering when scrolling files in the file manager (e.g. caja, nautilus, etc) and Firefox, even with firefox HW accel. disabled. The scrolling in the file manager made me downgrade to the 6600GT. AMD proprietary drivers aren't supported in Linux kernel 4.x, so I have to use the open source AMD drivers. If I use a GT710 or GT740 in the PCIex16 slot, there are no graphic issues whatsoever.
Obviously, getting the open source AMD driver fixed for the 4650 to fix those scrolling staggers is another option, but the person in charge of the driver will have to care enough to want to fix this. Reading the forums for a solution to this resulted in zilch.
Anything GF4 and older just don't run on Ubuntu 16.04, at least not on my system.
I have a GT710 in the PCIe x1 flavour, but I'm still stuck with the above A-E limitations. I suppose I could give up USB 3.0 entirely and backup my system by turning ot off and plugging a SATA drive into the Adaptec 6805T, runnig a clone, pull the drive out, putting the drive in the safe, and boot back up. But I don't want to have to turn it off at each small backup. This RAID controller doesn't seem to support hot plugging, at least not when I did the test.
Plan your life wisely, you'll be dead before you know it.