Firstly, nvidia only made soundcards as part of older chipsets on motherboards - about 5-8years ago methinks. Nvidia only makes Video cards and chipsets.
Arcgis will run satisfactorily on practically every modern CPU available on the market (except atom & low power chips) - Solved.
Gaming - depends mostly on Video card. A fast Dual core will easily out-perform a lower clocked tri/quad/hex core cpu (and they generally are clocked much lower). Sound output is also a consideration. Are you outputting via HDMI with 7.1 digital sound? or do you just want standard Stereo? or 5.1 analogue? optical out?
First of all .. what country are you in?
In the USA $3K will get you a top of the range gaming machine.
In Oz, it'll get you a mid range gaming machine.
In Vietnam, you'd be lucky to get a low-end dell netbook
Seriously though, buy yourself a pair of 24" LCD monitors, a decent Video card, a decent 64-128GB SSD with a separate 1-2TB HDD for storage.
From there, you can start with the real decisions -
What manufacturer & model of CPU - gaming / Arcgis really only need a fast dual core CPU. Hardcore video conversions might warrant a quad/hex cores if you do it often while using your PC for other things.
Which video card - how much do you want to spend? What features do you want? Dual DVI - HDMI output? VGA/DSUB output? TV Input/output?
Which Motherboard (depends on your choice of CPU) - what features do you want on your motherboard? SLI video cards, extra SLI slots, USB3, how many SATA ports, Sound Chip, chipset performance & etc.
RAM - Depends on how much performance you need (gaming), and how much you want to spend.
Cases - depends on video card & CPU you choose, and how many drive bays you want, whether you want it for great ventilation or silent operation? What ports do you want, how big do you want the case?
Power Supply - depends on video cards & CPU you choose.
Optical Drive - Bluray or DVD writer?
Keyboard / Mouse / Speakers/etc,