Re: I just got...
I have a GeForce GTX 770 in an older AMD desktop
That combination will also work, but it is extinct today. You get Nvidia _ONLY_ in Intel nowdays and _ONLY_ with Optimus tech bundled if it is a mainline vendor because Intel forces the issue on that one for them to get a discount. That is definitely in the Your Mileage May Vary zone.
IMHO the old GTX 770 will probably run a bit hotter with nouveau compared to nvidia + Powermizer set to the dynamic frequency setting. It will however work and it will not melt. The difference compared to a modern laptop from a mainline vendor with nvidia GPUs is that they _WILL_ melt unless you have the dynamic frequency on. In fact they will melt with either nvidia or noveau unless this is enabled. The guilty party is the Intel Ultrabook clusterf*** (sorry spec) which specifies geometry which makes proper discrete GPU active cooling (as needed by the chipset at full blast) impossible. While a discrete GPU laptop in theory is not compliant anyway, they are usually top of the line models in a line-up where the lower ones are ultrabook compliant (and thus eligible for volume discount on Intel chipsets). As a result, they inherit the deliberately crippled thermal design.
So you have to thermal manage via frequency throttle which nouveau does no have. You get that only with the binary driver and only if it works correctly and has magic incantations in xorg.conf