Manchineel

I'm SLOWLY digging out from under the mess of this new editor.  BRING BACK TEXT TAGS. PRETTY PLZ.
 
Note: It's getting complete, somehow. Post your complaints corrections and additions below. Everything is my opinion, even if it has a graph or flies in the face of something Linus said.
 
First watch this:
 

FAQs:

What's the most important thing I can do to improve my audio experience?
 
 
I have a low impedance headset. People tell me that onboard audio is terrible and a dedicated soundcard will improve my audio experience. How much will it really improve?
 
What is a DAC? How is it different from a soundcard? Which is better?
 
So, do I need a better soundcard or external AMP/DAC or is my onboard good enough?
 
I think I need a better soundcard. What should I look for in a sound card or an external AMP/DAC?
 
What should I look for in a pair of headphones?
 
I was thinking about buying good high impedance headphones in the future. Should I just get the amp/dac or soundcard now that would drive them, and buy the headphones later?
 
Should I get a cheap soundcard with virtual surround like dolby headphone or use a headphone with discrete drivers?
 
But I want a surround sound headset! What are the advantages of a good pair of headphones with a cheap mic?
 
OK, fine, but can't you just tell me what to get already and be done with it?  This is all very confusing!
FEATURES:

Headphones:
 
Surround Sound:
 
Speakers:
 
AMPS:
 
DACs:
 
Sources:
 
Microphones
 
Charts
 
Links to headphone and Amp reviews on LTT forums (Please check for broken links and report!):
 

Following your description and budget, it looks like the Pixio PX277h is the monitor you're looking for. Normally, a monitor with those kind of specifications costs around 700-850USD. Science studio has done a review about it because he was very sceptical:
I failed to find (didn't search long though) any tangible data about input lag.
 
Other than that, I personally own a BenQ XL2730Z Monitor which is a safe route and a guaranteed excellent performer for gaming.
Unfortunately, it's a TN so it may not live up to your colour-quality expectations, but at the same time it is a very good TN. It has commendable color representation for a TN Panel, just keep that in mind.
I could say the same about the Asus ROG Swift PG278QR

Here's a chart comparing the input lag between some gaming Monitors. https://www.rtings.com/monitor/tests/inputs/input-lag

Good luck!

not enough compound would result in all cores heating up. one core heating up over other is probably due to your work load only using one or two cores.