Smithy

It's really hard to tell which one is the best >_<
I'd probably say the headset

I personally am not sure on that topic.
I haven't needed to buy my own, only troubleshoot other peoples issues.
 
What I would recommend is making another thread 'Best Under $100 DAC/Audio Cards' and get the opinions of people that have more experience.
 
Best of luck, I hope it all works out.

I've read a couple posts where people took a kitchen sponge, wetted it down with isopropyl, then stabbed the CPU into it. You shouldn't be applying a lot (nearly any) pressure while sanding so there's not much worry of bending pins unless you're doing something wrong.

http://www.kustompcs.co.uk/cgi-bin/ss000003.pl?page=search&PR=-1&TB=A&SS=Lapping&ACTION=Go%21

Admittedly it would be easier with Intel than amd

I don't have any experience doing this to a CPU, but in the world of motorcycle racing mechanics use a flat pane of glass and sand paper o flatten motorcycle heads. To do this with a cpu you could use a piece of glass and very fine sand paper (2000 grit) and wet it to make it take even less off. It would be a really cool project but wet sanding is also very dirty. You will probably have to lap the heat sink as well for optimum contact.
 
EDIT: Stupid me I looked at that kustom PC link to late 

I know that kustom pc here in the uk do a lapping kit with all several grades of sandpaper / wet & dry paper & a piece of glass so you can see your results easily.
Personally I think it's very expensive for wat it is but you can use it also as a guide on the bits your need.
My Sysyems idles at between 20/22 & 27 degrees dependant on room temp & fan speeds, so it's not something Im looking at right now (also reluctant to screw with a new (ish) 5820k as there almost full warranty left. I went with 2 420mm rads to control temps & run at low fan rpm instead.

You use sandpaper to make the CPU surface as smooth and even as possible, back in the old days it could drop your temps by "up to" 10c.
 

the first time you pulled it apart you should have reapplied new thermal paste. perhaps you notice, after such a long time, the old paste got dried out? Anyways, not reapplying new or removing the pads and not putting them back, or back in their correct positions could have created more problems. Also take note that sometimes the new thwermal paste may need "break in" time.

I've seen 8350 I believe at almost 5GHz with a H100.
I think that for 5GHz, if you've got a good chip, you're going to need something like a Corsair H110, H105, NZXT Kraken X61, Swiftech H220X (pretty much the best AIO liquid cooler), etc.
If it's not necessary to get a liquid cooler, you could get the Noctua NH-D15. It's pretty much the best performing air cooler on the market right now, but it's quite big. And by quite big I mean really big.
Also, what motherboard do you have?