Getting back into WoW / Boxing, need hardware advice.

[MiRai]

(1) I’d prefer to 5-box with as few computers as possible (preferably 1)

This is what most people these days.

(3) I can go up to 4 monitors on my primary PC, but I don’t believe adding a second GPU to my primary PC is an option as the Gigabyte Z68x-UD3H-B3 motherboard has 1 16x and 1 8x 2.0 compliant slot, and if a second card is added the 16x slot runs at 8x, which I assume would hurt performance a lot more than it would help it?

It's highly doubtful you'll be able to saturate the PCIe lanes on 8x.

SLI 16x/16x VS 16x/8x - http://hardocp.com/article/2010/08/1...2#.UZ4ft7XVB8E

(4) The Keyboard/Mouse control software I used in my old setup (Multiplicity) doesn't work well in multi-monitor setups, and is very awkward to use to navigate to the top left/right monitors, so it’s not ideal for fast reactions. I haven’t found a replacement that works well for gaming (mouse movement goes crazy when using Synergy and Share-Mouse), so a 1-PC or 2-PC solution using the bottom 3 and top center monitors (primary and secondary PCs only) would be best.

I know nothing of Multiplicity. Most people use Input Director because it's free and seems to do everything that Multiplicity does (except centralize audio).

Everyone says that boxing 5 on a single PC is very doable with even a medium quality graphics card, especially if you use DX9. However I’m not sure if anyone is doing 5 large windows on a single PC with a single GPU, and I haven’t purchased the 670 yet to test.

I would say that most people render each of their game clients at the resolution of their main client so that mouse broadcasting is 1:1. This really comes down to which software you'd be using because if you're going to be running something like Keyclone, then no matter what you do your game clients will render at the resolution they're shown on your monitor, whereas, if you use ISBoxer, then even though the game clients look scaled down, they're still rendering at the resolution you tell them to (by default -- this can be changed) so that mouse broadcasting accuracy is preserved.

This is on a person-to-person basis, though. It's hard to judge how a person truly has their clients set up via a screenshot unless they give a lot of details about it.

I saw a post from MiRai that said a 3/4GB card couldn’t do it in DX11.

...using the Ultra preset @ 1920x1080 x5. There are those that claim they can "run" their clients at Ultra @ 1920x1080 on 5x game clients using DX11, but everyone's definitions of "run" and "playable" are vastly different.

I saw a post from Ualaa saying he’s using running 4 slaves on a 1080x1920 secondary monitor (in portrait maybe?) in DX9, but I’m not sure what size they are.

Pretty sure he was rolling around with DX11 before he quit, but I could be wrong.

MiRai said he had some issues using 3 monitors as his performance was choppy, but that most people didn’t have this issue.

I can't imagine I said this recently? This sounds like something I said back when I was using a Q9550 and 2x GTX 260s... which was 2+ years ago.

MiRai posted that running different resolutions on your monitors caused significant performance issues for the 4xx and 5xx cards. I didn’t see any posts that specifically listed different resolutions, but saw many listing the same, though I certainly could have missed them. Does this issue still exist for the 6xx cards?

Significant performance issues? Are you talking about the issue where you run two monitors of different resolutions (monitor resolutions, not game resolutions) off of the same GPU, that GPU doesn't downclock?

If that's what you're asking, then that doesn't cause significant performance issues, but as far as I know, yes, the downclocking problem still exists; but if it really bothers you then you can manually change the P-State of each card through nVidia Inspector.

If you had the equipment listed above available to you, and had the option of buying an additional 670/680 and Game-dedicated SSD, how would you configure this boxing setup if it were yours?

Use the 2600K system and get a better GPU.

For the GPU you most likely want a non-SLI setup because SLI will give you only very low increase in performance but alot of problems and issues. My GTX 580 is already overkill for that setup since I'm running into CPU-limitations when LFR-ing rather that GPU-limits. I'd still replace that HD 6870 because WoW performs better on Nvidia cards and you want a card with 3-4GB of video memory for 5 clients.

This is something I've been meaning to address for awhile now because I've been running SLI for the last few months and the performance increase I'm seeing is amazing. I'm able to push video settings beyond what I normally would be able to using just a single card (or I would be forced to split the load between two GPUs on separate monitors).

Here's some quick proof I whipped up this morning: SLI VS NoSLI
(hover over the image, click the gear icon, and choose to view in full resolution if you want to see the full image)

I've become quite attached to that layout and running all five clients on a single monitor, so I don't have any 1920x1080 comparisons for anyone.

For anyone that looks at those comparison images, know that SLI has never been a proven technology while running multiple game clients and its results may vary greatly from setup to setup or from game to game. The images I've posted above aren't saying, "SLI is a must! Go out and spend more money now!" because if you happen to run out to the store and purchase a second (or third or fourth) video card to SLI together and it doesn't work as awesome as you thought it would, I'm not responsible.