I'm a bit of a newbie, so I'm just going to throw as much information as I can at you and hope that it's all relevant. Not sure if important, but my computer has had Ubuntu since 8.04 (I just kept upgrading)
So back in fall 2012 I bought a Nvidia gtx 560 video card that doesn't have optimus technology, and I popped into my PCI-e 16x slot and it pretty much worked from the get go. It was almost effortless how easily my computer (Ubuntu 12.04) switched from its internal onboard ATI chipset to the newer GPU. I still had issues running the new XCOM game, but Minecraft played with ease, it wasn't until 12.10 that the XCOM game (with wine 1.5) that it started working, and I enjoyed myself thoroughly. However the problem started when I decided to plunge head-first into upgrading the second 13.04 was released (I forced the upgrade). All these issues came up that prevented me from operating my computer properly. So I reformatted back to 12.04, since then (it's been a couple of months now.), my video card can't be detected (I've tried to disable display port and switch to GFX0 in BIOS), but I can't seem to find the right driver for it either (I've tried nvidia_current, 304, and 310); everytime I've installed a driver and rebooted, I switch the display cable over to the video card, and my monitor immediately goes to sleep, when I switch it back to the onboard, it runs like normal. I've remove and reinserted the card countless times, cleaned the slot and the rest of the motherboard of dust, I've done research into other posts online but to no avail. I'm just about ready to become a crazy cat-person that swears off all technology if I can't make this work. Can anyone help me?
P.S.- I'm deluding myself into thinking the card is still operational because I can both hear and feel the fan running when the computer's on and the card plugged in to the PSU. Also, when I removed it before, I noticed the 4 to 6 pin connector cables (4-pin is one row, and the 6-pin are two rows of three) it uses are somewhat loose (I can almost pull one of the pins completely out on the 6 side). I tightened that up as best I could but I still keep getting "No signal, monitor going to sleep"