Upgrading CPU/mobo for SLI 970

[Koizumi]

I've been getting low fps benchmarks and in games that isn't close to what a 970SLi should be bringing and people have suggested I upgrade my CPU and motherboard.
Here is my current CPU/mobo:
Intel Core i5-2500K OC'd to 4.2GHZ
MSI P67A-G45 (B3) LGA 1155 Intel P67 SATA 6Gb/s USB 3.0

1) What will you be doing with this PC? Gaming? Photoshop? Web browsing? etc
Gaming
2) What's your budget? Are tax and shipping included?
600$
3) Which country do you live in? If the U.S, please tell us the state and city if possible.
Phoenix, Arizona
4) What exact parts do you need for that budget? CPU, RAM, case, etc. The word "Everything" is not a valid answer. Please list out all the parts you'll need.
CPU, motherboard, and maybe RAM
5) If reusing any parts, what parts will you be reusing? Please be especially specific about the power supply. List make and model.
2 x GeForce GTX 970
Antec TruePower New TP-750 750W
G.SKILL Value Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333
Creative Sound Blaster ZxR
CORSAIR Hydro Series H100i
Intel 320 Series
Western Digital WD VelociRaptor
2 x Western Digital WD Green WD30EZRX
6) Will you be overclocking?
Yes
7) What is the max resolution of your monitor? What size is it?
2560x1440, 27 inches
8) When do you plan on building/buying the PC?
This Friday
9) What features do you need in a motherboard? RAID? Firewire? Crossfire or SLI support? USB 3.0? SATA 6Gb/s? eSATA? Onboard video (as a backup or main GPU)? UEFI? etc.
SLI, at min one PCI Express x1, 4 to 6 SATA ports 6Gb/s
10) Do you already have a legit and reusable/transferable OS key/license? If so, what OS? Is it 32bit or 64bit?
Yes, Windows 7 64bit


I have my eye set on Intel Core i7-4790K and I'm not sure on motherboard or RAM(dunno if i need to upgrade that). If the PSU is that big of a problem I'm willing to spend the extra money for that next week.

 

[Dangman]

I don't think you should upgrade just yet: your current system as is should be fine for GTX 970 SLI. I think you're looking at a driver, OS, or software problem. Especially considering that the GTX 970 was barely released this month so the drivers aren't exactly "solid".

With that said, remove your sound card and verify via the program GPU-Z (google, download, and run it) that your cards are indeed running at x8 speeds using GPU-Z's PCI-E test tool.

 

[rhansen5_99]

I would agree with Dangman, you are really not going to see that much of an improvement moving to socket 1150 at this point especially if you are oc'd to 4.2 GHZ.

What video cards did your upgrade from / did you use the driver sweeper to clean out the old stuff?

 

[Koizumi]

I would agree with Dangman, you are really not going to see that much of an improvement moving to socket 1150 at this point especially if you are oc'd to 4.2 GHZ.

What video cards did your upgrade from / did you use the driver sweeper to clean out the old stuff?

I used Display Driver Uninstaller. The mobo might just be too old I think? I just can't figure out why games run nearly the same with SLI enabled or disabled. And in some games single GPU setup is beating SLI.

According to GPU-Z the cards are running at PCI-E 2.0 x 16 @ x8 2.0. Thats with my sound card with its drivers uninstalled and with them installed.

My BIOs is updated(latest version from MSI is from 2013-01-09)

 

[Dangman]

I used Display Driver Uninstaller. The mobo might just be too old I think? I just can't figure out why games run nearly the same with SLI enabled or disabled. And in some games single GPU setup is beating SLI.

According to GPU-Z the cards are running at PCI-E 2.0 x 16 @ x8 2.0. Thats with my sound card with its drivers uninstalled and with them installed.

My BIOs is updated(latest version from MSI is from 2013-01-09)

I really don't think it's a case of your motherboard being too old. The GTX 970 isn't a massive jump in performance to where PCI-E 3.0 x8 at a minimum is needed. PCI-E 2.0 x8 translates to PCI-E 3.0 x4 performance. Awhile back, TechPowerUp did an article showing that a GTX 680 performed pretty much just fine on PCI-E 3.0 x4 speeds:
http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/24.html

Relevant portions:

- Our testing confirms that modern graphics cards work just fine at slower bus speed, yet performance degrades the slower the bus speed is. Everything down to x16 1.1 and its equivalents (x8 2.0, x4 3.0) provides sufficient gaming performance even with the latest graphics hardware, losing only 5% average in worst-case. Only at even lower speeds we see drastic framerate losses, which would warrant action.

- PCI-Express 2.0 x8 is still a viable mode for 2-way multi-GPU. This is the mode most Core "Sandy Bridge" platform users will end up using for multi-GPU, and differences between PCI-Express 2.0 and 3.0 x8 is just 4% and 2% for the GTX 680 and HD 7970, respectively.

Even if you looked at worst case scenario, a 5% performance loss isn't worth spending $600 to fix. Unless you can find other information with actual data showing that the GTX 970 SLI requires a PCI-E 3.0 x8/x8 setup, there's something else wrong with your setup.