Yes.
Although for a device like a fan, we don't really assign a resistance value to them, because they are nonlinear. That means that the current draw is not based linearly on voltage. Loading the fan increases current, startup current is more, and as someone else pointed out, the circuits in a brushless computer fan may limit the power drawn even when more voltage is applied.
Although my experience is that I've applied up to 18 or 19V to 12V computer fans and they've run faster. However, you are taking the risk of overheating the internals of the fan.
Ok, I think I am getting it. The PSU values of 19V and 5.27A are just that it will push 19V out and the amp is a rating, not a constant value. Meaning that it can push out max 5.27A or less, just not more. No matter what the amp draw is (as long as it is below its rating), the voltage will always be 19.
If that is correct, then the resistance will vary across each device connected to it. So I have a fan that is taking 19V and drawing 0.25A meaning the resistace of the fan is 76 Ohms. The peltier would have to have a resistor set up infront of it to limit the voltage but at the same time it would limit futher the current available and pull even harder for that current, but would still have the same affect on the PSU.
The device itself will pull the amps out instead of the PSU pushing them in. If the device exceeds the PSU limits, then things happen that can be bad.
Is this correct or am I still lost in the woods over here?
Generally, when you overload a power supply, the voltage either drops as the load resistance goes down, or suddenly cuts off. It depends on how the power supply was designed.
Rather than use a resistor to limit current to the peltier, which will cause the generation of a lot of heat, I'd get a desktop computer power supply and modify it to work without a computer. The 12V outputs will generally put out a lot more than 10A.
Basically, you need a minimum load on the 5V line, and a way to turn on the power supply. This one does it as an external adapter:
http://makezine.com/projects/computer-power-supply-to-bench-power-supply-adapter/I repaired a peltier junction cooler, replacing the rusted out fan with two 12V computer fans, and found a 12V 12A open frame power supply surplus, and put it into a case with a fan cooling the power supply so I could run it on AC.