I have them on my 2600k.  All is well on pci-e 2.o

DD4 will release on mainstream market with Skylake not Broadwell.

If you can wait for Broadwell and mainstream DDR4 then wait, if not just get a Z77 motherboard with PCIe x16 and get back to gaming or what ever you do.

wmmills
Def wait for skylake. SLI on your rig now with 980's even will be fine at x8 with 1080p. If your wondering about much higher resolutions and multi monitor surrounds etc... then you may see some issues. Luckily the sandybridge chips overclock easily and highly while staying cool so you may get some mitigation there for either scenario. Im keeping mine till I wear it out and its little tongue is hanging out!!! :P

Yeah I was afraid of that. I figured the PCIe 2.0 bus could handle single monitor setups fine. I just wish their was more info on multi-monitor setups and higher resolutions, just to give me a general idea on if the system could even handle it decently b4 I go in ePeen first... and how much of a performance impact I could expect.

Whach
Give this a .  Essentially, pcie3.0 will give you around 1-2 FPS more @ 4k in SLI.  Not that much at all.  Unless the next iteration of i7 brings something spectacularly new in performance, as Sandy Bridge did, I'd stay with the 2600K and OC it (even if you don't OC it should be fine). I have mine at 4.5ghz easy and stable. No issues with my SLI 980's @8x on a 2560x1600 monitor using all the eye-candy I can throw at it.  So don't worry and save yourself some ca$h =)  Multiple 1080p monitors wont be bottle-necked by pcie2.0  
However, if you are building a new system from scratch, obviously get the latest components.  At this rate, this will be my longest lasting rig yet.  2 yrs running and not much worth upgrading to in terms of CPU's. 

Indeed, the 2600k was launched 3 years ago now, and is still going strong! Has yet to hit max with anything I throw at it. I know that IB and Haswell are more efficient in both power utilization and processing clock for clock. But most benchmarks only give them a marginal advantage. Now, I just wish I had done my research and got a board that could utilize the IB's PCIe 3.0 capabilities.

Back on topic though, I didn't realize until just now that the 980's have a 256bit memory interface with a bandwidth of 224GB/s vs the Titan's 384-bit with 288.4GB/s. 
So if the Titan can handle it @ 4k on x8 x8, then you're right. The 980 shouldn't have any issues.

I don't know why people with Intel Sandy Bridge and Bloomfield example worry so much about bottleneck...
They are not for overclocking competition but for gaming they are OK... Compare example result in Firestrike between overclocked i7-950/960 and Ivy Bridge, Physics score and Combined score. Difference is not half and Graphic card score is not much lower... They are still excellent for gaming...
Even for GTX980 SLI. GTX980 SLI is maybe now best option...
SLI power consumption is little more than Titan Black, performance are double and price is half.
And I don't believe in difference between 2600K OC and i7-4790K.
Sandy can work on same speed 15-18C colder and difference in games could be max 1-2-3fps.
If you choose for gaming, for notebooks is Haswell probably better.

robt1386
2600k and single gtx980 is fine but with sli you will be losing performance and not worth it imao.

lol  ignore this 

Why only Valley 1.0.
Compare Graphic Score in Firestrike Extreme and 3DMark 11 Extreme, Unigine Heaven 4.0
You will see very little difference...

Vlada011
I don't know why people with Intel Sandy Bridge and Bloomfield example worry so much about bottleneck...
 

Common misconception that games become equally as demanding as the hardware performance increases between generations.

Whach
 
 
Apparently, the new Delta Compression algorithms in Maxwell make up that extra bandwidth most of the time.  Having said that, I fully expect that to be on top of any extra 384/512-bit bandwidth that ti version may have.  If 4K+ is going to be the future, the more the better! 

Hmmmm, now I wonder if I should wait and pair up the Ti versions with my 2600k in the hopes that they have a bit larger memory interface.  
Especially if I plan on giving Surround a try with this rig.

i7-950 OC on 4.0GHz give about 9.000 Physics Score in Firestrike, from other side 3770K OC on 4.5GHz about 12.000.
i7 Bloomfield or Sandy Bridge Processors can't be bottleneck for 1-2 graphic cards today. That's insane.
PCI-E 2.0 is only bad thing in whole story, nothing else.
For Benchmark competition and 4770K is overcome, out of date, but we can't choose Processors like that.
They are not so important as graphic cards for gaming. i5-2500K hold Titan Black easy on stock or OC.
I expect 0-5% improvement when I cross from i7-3770K on i7-5820K but only because it's nice architecture and not bad for OC and people predict long life.
I don't expect improvement in games at all, only in some numbers maybe and new memory standard. From CPU side I could stay here 3 years more easy.
Graphic cards are important and need to be change on 24-36 months MAX, 24 months better if you want to enable filters x4AA.
Processors market is full of models with absolutely same performance in games, some little percent decide almost nothing.
Maybe on 100-200fps we have 1-2 fps difference, nothing else.
Intel literally play with people... competition not exist, they exist but out of race completely.
When they should launch Haswell they talk about integrated voltage regulator in die as new miracle, people look about that as something... best..
Now new story is completely removing integrated VRM and never think about that ever and everybody impatience wait that as one of improvement of new architectures...
 

Whach
I have them on my 2600k.  All is well on pci-e 2.o

Hi there. I just bought a 980ti with the same mobo. I'm running the latest Windows 10 and 1.) I can't get the mobo to post with the 980 ti in slot 1 (truly did all the logical troubleshooting) 2.) WHen I use iGPU to boot after clearing all drivers I can get the system to recognize the card. After installing Nvidia drivers, on reboot I get BSOD with a "nvlddmkm" error. Since you have SLI 980s running on the same board, I'm just interested to hear if you have any ideas to help. I can't PM yet. Otherwise I would have.