Upgrade paths

[pantomime]

Hello Everyone! I had a few questions on some pc upgrades and wanted to get your opinions.

Build 1:
5k speed sata drives
FX-8120
8 gig 1333 ram
gtx 560 ti
windows 8
Linux
600w corsair psu
27" samsung lcd 1080p

I have sennhieser ear buds plugged in and I get terrible line noise. I get this from any speaker / headphone I plug in.

Build 2:
i5 2400k
gtx 460
4 gb 1333 ram
windows 7
23" LG 1080p

Our gaming gauntlet : The Secret World, WoW, GW2, Dota 2, The Sims 3, Civ 5, maybe the new counter strike.

Other notes: I have been looking into going 1440p on Build 1, I crave that real estate. My spending budget is $800. Parts from one build can go into the other. Here is what I am looking at:

1440p monitor (can a 560 ti run well at that resolution)
1866 Ram kit (8gig min) (FX-8120 natively runs at that speed?) $100 ?
660 ti / 670 / 680 / 7950 / 7970 $200 - $500
128G SSD (OS and 1 or 2 other games)
Sound card (Xonar or something, to get rid of that line noise) $200

just looking at cost vs performance and what will give the most umph until I purchase the rest. Thanks for taking the time to read this.

 

[Dangman]

So many questions to ask:

For build 1:
1) Did you mean 5400RPM drives?
2) Which Corsair PSU do you have?
3) Which mobo do you have?

For build 2:
1) There's no such thing as the 2400K. Did you mean Core i5 2400 or Core i5 2500K?
2) Which mobo do you have?
3) What PSU do you have for this?

For both:
What exactly did you mean by "until I purchase the rest"?

In addition to the seven questions above, please answer the stickied "ANSWER THESE QUESTIONS FIRST" so that we can help you better.