Those PCIe 2.0 vs 3.0 benchmarks apply to current gen cards (HD7000 and gtx600 and prior)  I am fairly certain that someone with Z67 board and sandy bridge would be running in to bottlenecks with a dual Titan sli running pcie 2.0 8x8x. 3-4 years down the road when a single card can offer dual titan performance, pcie 2.0 may no be enough. Also since steamroller is using AM3+, there is no reason why he cant upgrade to that in a year or two...

If money was of no concern, Id definetly say go for fx 8320 (not 8350) and a beefy water AIO cooler and get it to 4.8 Ghz...but in a build hes putting together, I dont think its worth 50 bucks more.

Oh god. I've ran tests with my Triple Radeon 7970's with PCI-E 2.0 against 3.0, there was no difference outside of compute. None, nada, nil, with the rate GPU's are advancing these days, it will be a long time before PCI-E 2.0 ever becomes a limiting factor, by then it would be time to overhaul the machine anyway.
People still drop high-end cards into Socket 775 (PCI-E 1.0 16x = PCI-E 3.0 4x) motherboards without a problem or massive performance impact.

PCI-E 2.0 16x = PCI-E 3.0 8x in terms of bandwidth.

Also, don't hedge your bets on Steamroller, it hasn't been confirmed to be coming to AM3+, AMD may release a new socket, A-la. AM4 possibly requiring a new Motherboard.

Here is a vid showcasing limits of PCIe 2.0 vs 3.0...CallsignVega has some awesome videos and ing eneral knows his shit.

http://www.youtube.com/watch?v=S0-xcxAvu54

I know the 3.0 is just 2.0 X 2 in terms of speed but if you throw enough GPU horsepower at it, you will see bottlenecks at some very high FPS rates, depending on the amount of PCIe lanes you have available. The board he is getting is X16, X4 for example...

Sure it took Quad GTX 680 to hit this limit on an X79 chipset but this mobo is x16, x8 ,x8, x8 in quad sli with 40 total lanes.  Some AMD boards are PCIe 2.0 x16 lanes total and x8,x8 in SLI/crossfire you may run in to a bottleneck as well. This bottleneck may happen at 100+ fps and AMD cpu may already bottleneck the rig before that happens. However for something like 3D vision where its all GPU and not CPU, it will be evident even at lower frame rates.

As far as Steamroller, you may be right... I am going simply on what has been reported on thus far. 

http://www.theinquirer.net/inquirer/news/2208525/amd-sticks-with-socket-am3-for-steamroller

Ok, I got everything ordered. Only thing changed from above is the PSU which is now a Corsair 650HX for $110. I really didn't intend on spending this much on a power supply, but further thinking made me realize this will prevent the need for a new power supply on the next computer down the road.

My other question I have for you guys, what is the GHz edition of the 7870? Cause the one I ordered is the Sapphire Radeon HD 7870 GHz edition, and I don't know if that is just the normal one or what.

7870 GHz edition is the normal 7870 that AMD released. Since initial release, some of the vendors released cards called 7870 PCS+, "MYST" edition or 7870 XT. These cards were actually 7950s with some cores disabled, but clocked much higher. This card is a good 20-30% faster than the 7870 Ghz.

They are usually listed toegether so they are hard to spot. For example:

http://www.newegg.ca/Product/ProductList.aspx?Submit=ENE&N=100007708%20600100181%20600286767%20600298540&IsNodeId=1&name=Radeon%20HD%207870%20GHz%20Edition

Out of those cards, "PowerColor PCS+ AX7870" is faster then all of the rest.  It's quite confusing to someone that doesn't follow this...

So does the Sapphire version being 50MHz higher make any real difference?

Also, out of curiosity, since I am going with the AMD card, is overclocking the 6300 relatively easy?

Out of the box 50 mhz more won't make a difference. But these cards are really easy to overclock even further. Take a look at this guide...

http://www.guru3d.com/articles_pages/radeon_hd_7870_overclock_guide,17.html

As far as the FX6300, its very easy to overclock but you need a good cooler. Hopefully you picked up an aftermarket cooler as the stock one is noisy and won't allow any overclocking. Something like H60 AIO watercooler or Noctua D-14 will be great and give you 4.3-4.5 GHZ overclock no problem. 

Well, I don't intend on overclocking initially if everything is quick enough for me (which I don't see why it won't be). That being the case, if the computer is staying cool enough with the stock cooler, I'll be keeping it as is for a few months. Down the road, however? Yea, its very likely that I will overclock things to get a little extra speed out of it, and I'll probably be spending a few bucks on better cooling.

Yeah thats a good strategy.

Out of curiosity, are you able to exchange some of these parts? Like if you bought at TigerDirect, do you have a store near by?

Reason I ask is that power supply... $110 is a lot of money for a 650W PSU, no matter who the maker is. You should be able to pick up a 750 W PSU that has 4 PCIe connectors. This will help if you want to go crossfire with 2 7870s down the road. 

When 7870s are 100 bucks on ebay, you can pick 1 up and double your graphics performance since your motherboard supports crossfire. But that PSU doesn't...

I can still cancel the order. It hasn't been fully processed yet. Lemme see what I find, as I never really thought about the dual gpu solution down the road.