Just got a new BenQ GW2480 monitor but its power supply cable is too short. Looked around and found this other cable that actually is long enough. 

The cable that came with the BenQ says that it's 125V 10A and 1250W. Looking in the link, it says that the other cable is also 125V and 10A, but it's missing the 1250W, though I suppose that's not so significant, it's the voltage and the amperage that matters, right? 

Not really sure where else to ask, this kind of stuff makes me wish I studied electricity. 

Ohhh, that actually blew my mind. Thanks a lot, bud! I really need a quick course in electricity. 

That's the cable specifications that the cable supports. Meaning max. 10A at 125V. But your monitor is not running at 1250Watts. There should be a label near the PSU on your monitor on what the consumption is.
But as Bristow said, the cable is fine. It's a basic cable for those devices.

The cables with IEC 60320 C13 plug are normed and very common for PC hardware (PSU, monitors, many old TVs...)
I have at least a dozen of them for replacements.

https://en.wikipedia.org/wiki/IEC_60320#C13/C14_coupler

So I have used the unit in two 1-2 hours sessions, and every time after I turned off the monitor, it made a series of subtle popping sounds, very sporadically, they aren't too loud, but they're annoying because it's a first to me. Didn't happen immediately after I turned it on, didn't happen in overall use either, only after turning it off, probably for half an hour and then it stops. I've read online and it seems it could be thermal expansion or something. Others suggest that it could be something more serious, but I dunno. Could I live with it or should I return it?