All, 

I wanted to share my frustrating story in case anyone else is going through the same thing and if there were any solutions out there. 

I custom built a new computer, specs:

i5 4430 @ 3.0ghz
GA-Z87m-D3h
16GB, gSkill @ 1866mhz
RAID-0, SSD 256GB (2x128gb, for OS)
1TB HDD (for storage)
EVGA GTX 760SC 2GB
CoolerMaster 550w PowerSupply

Windows 8.1 64bit.

Installed OS and it ran fine, but I noticed, that on some boots I would get an unusually high DPC latency caused by my nvidia driver (checked with latencyMON and WPA). All drivers, including Nvidia ones were up to date. There didn't seem to be a reason for it. 

My board had on-board video, so to troubleshoot I removed the 760, and no issue. 

Up until this point I was using HDMI as the primary connection from my card to my monitor. I had tried the display port at one point, but the OS wouldn't post with it. As soon as I reverted to the HDMI it would be fine, but the DPC issue was still there. 

I thought it was definitely the card/driver. I ruled out the driver based on it being the most up to date. But I didn't think - though it could be - a hardware issue because it was intermittent and the card worked extremely well on most boots. I was about to RMA the sucker and was dreading the turn around and the potential to get a card back with the same issue. 

So, in a last ditch effort I switched the connection from HDMI to DVI. Issue seems to be solved. 15 boots since the change and no DPC issues. For sanity, I tried it again with the DisplayPort connection and it seemed to work fine, but on the fourth boot I got a bit of DPC lag. 

Because all of those ports are digital, its all the same signal coming out, the only difference is the audio aspect of HDMI and DisplayPort. 

Anyone else run into something similar? Would really like to know and how you resolved. I don't mind using DVI, just a bit pissed because I spent $ on a displayport/hdmi monitor.

P.S - Noticed that when using Displayport/HDMI colours seem to be muted in-contrast to DVI - potential symptom? I've also got a few "kmode_exception_not_handled" BSOD... not frequent, but enough.

No lag during POST, only after OS is loaded. Symptoms include slow reaction time, distorted audio and clunky transitions.
Again, an intermittent problem that only occurs with HDMI and DisplayPort - curiously not with DVI.
 
Thanks for your reply, I've been banging my head on this for about a month.
 
TD

The HDMI is not shielded as well as the on board or a stand alone sound card is, so it tends to produce more "noise" which can increase the DPC latency. If you don't use the HDMI port for sound, I'd recommend disabling the Nvidia High Definition Audio Controller in the Device Manager. To do so, go to the Device Manager and look at the Display Adapter. Under Properties, check what PCI_Bus_# the video card is on. Then under System Devices, scroll down to High Definition Audio Controller. There should be at least two entries. Check each one and look for the one that's on the same PCI_Bus_# as the video card. That's the Nvidia HD audio controller, go ahead and disable it. This HAS to be done under System Devices, not Sound, Video, and Game Controllers, otherwise it will re-enable on reboot. See if the DPC latency is any better with that disabled.

Is DisplayPort not shielded as well?

Tried a couple things...
1. Moved my router/WiFi modem from the top of my case to the shelf besides it.
2. Disabled the HD Audio Controller as prescribed.
3. No lights were on in my office.
 
DPC Latency continued to happen via DisplayPort. In addition, Win8.1 will not cold boot into OS with DisplayPort . I disabled secure boot in the bios just to be sure it wasn't that.  I see a black screen, mouse cursor, and an old-school blinking underscore in the top left corner of the screen and the system auto resets. 

Couple interesting observations....
1. Was doing a "control" reset test with DVI. Power on/off, got some DPC latency lag with DVI, so it does happen with it, just not as often. 
2. Colours continued to be muted via DisplayPort vs. DVI
 
I think its hardware... any other ideas before I RMA? 

Did one better, put it into another rig. Seems to be fine...display port worked perfect, no unsaturated colours, no dpc latency.

Could it be a PSU problem?

I'm gonna do a barebones test tomorrow and see what happens.

So I think the 3 issues were all unrelated.
 
1. DPC Latency - Solved. Went into my BIOS and turned all the features that I didn't use/understand off. Vd-t, XHCI/EHCI handoff etc. Didn't start going through them 1 by 1. Just happy its gone - anyone think they know which one it could be?
2. The DisplayPort Power issue I thought was a PSU problem. I swapped my 550 out for a 750 and it seems to have fixed it. Though, it may have been a driver issue because I get something similar now, blackscreen+cursor. Difference is its not isolated to display port anymore, its everything. Still sorting this out, not sure what to do yet.
 
3. Muted/Unsaturated colours and driver settings not sticking - Seems to be a known problem with no fix.
 
That's all. Maybe this will help someone at some point.
 
 

Interesting. I did a CMOS reset and it seems to be functioning fine - good call. Hopefully that solves it.
 
BIOS was up to date - F10.

Seems to be an incompatibility with the board (GA-Z87m-dh3, F10), my gtx760's displayport and probably something to do with UEFI/Windows8. Whenever it did a reset boot, it would work. Fast boot was a problem. 
 
I give up. Gonna use DVI for now. I just formatted to rule out driver issue, and played with BIOS settings to rule out any of them. 
 
Plugged in the DVI and haven't had any problems. Not gonna mess with it. 
 
 

I'm a putz. 
 
Displayport Issue is Solved - It was the cable. It wasn't VESA compliant and had its pin20 connected which gave feedback and effected boot. I covered the pin with a small piece of electrical tape, and the boot issue was solved. It did function on the older board, but I assume it was because the power on that board was lower?
 
Only thing left is the colours, but that seems to be a common problem with a fix being worked on. 
 
 
 
 

Just wanted to thank you for posting the solutions to the problems you encountered. I have the same Graphics Card and motherboard and was encountering the DPC issues you describe. Whilst I haven't tested it extensively, I disabled Intel Virtualization Technology along with all the legacy support options and it already seems to be behaving better (I already had all the Win8 features disabled as an attempt to solve this problem). Before all it took was to start Spotify for the DPC to sky-rocket to about 5ms. Now it peaks at about 700 us, which whilst not great isn't too bad. Strangely
 
Just one question though, were you encountering Display Driver not responding errors about twice a week, or is this a problem unique to my setup?
 
Thanks again for posting your findings, it had gotten to the point where I was about to install Win7...

I'm not sure installing Windows7 will fix the problem. The issue seems to be with the board/proc and how it interacts with the driver. 

I was thinking the same thing, but its working now. I have all Win8 features enabled including DynamicTick, which I did previously disable to rule out. 
 
What are your complete specs? What connection are you using for your monitor (DVI, DP, HDMI?) Do you have your OD on a RAID-0? SSD or HDD?
 
Most importantly, did you disable EVERYTHING in your BIOS?  I literally disabled everything... even xHCI and eHCI (USB 3.0 controllers) then brought them back 1by1 by necessity. 

HAHA - mine started out as a hackintosh too. I scrapped it, it wouldn't run stable... it would lock up constantly. Are you using Clover EFI?? or Chimera? 
 
Curious - if you disable the driver for the vidcard in windows, does the problem persist(mine didn't)? In addition, if you just use the on-board one, do you still get high DPC latency?
 
 

I write iOS apps and so having a hackintosh is very useful, fortunately it is stable enough for my purposes. I am using Chimera and I realise just now that I haven't tested that it still works after all the tweaks I've made in the BIOS... Hopefully it still runs...
 
As for disabling the driver, I will try it, however, it isn't a solution to the problem as AFAIK the default driver is a CPU renderer which then just populates the GPU's display buffer... Essentially making the card a £200 DVI port...
 
I've also tried xperf to diagnose other potential causes (other than graphics related tasks) and there weren't any of significance. The NVidia driver and the DirectX Graphics Kernel were far and away the main culprits.
 
Also checking out the Event Viewer it is full of nvlddmkm errors (code 14) which seem to correspond to periods of high DPC latency... Annoyingly the nature of errors means you don't get an error dump..