Recent System Build: (before fully understanding CPU lane limitation)

MSI godlike Z390 (because I thought 4 16x motherboard lanes would actually give me 64 lanes..)
I9-9900k
RTX 2080 (would have gone for 1080 ti if I'd have found one cheaper)
32gb ddr4 3000 (ballistix)
970 pro 512 nvme
2TB 860 evo SSD
be quiet dark rock pro 4 cooler (love this cooler)
be quiet 700 watt power supply
2 Decklink Quad 8 channel SDI cards (was hoping for total of 14 inputs 2 outputs)
Focusrite 18i20 usb 3.0 audio interface for multi channel audio input


After installing vmix we noticed pretty quickly that we were getting GPU overload. On running GPU-Z we noticed our rtx2080 was only running 4x @ 3.0. (I then installed the GPU into the correct top slot on the motherboard and took out one of the blackmagic cards (noob computer build mistake) After doing this we were able to get it running 8x @ 3.0. Only when I took out both blackmagic decklink cards could I get the GPU running at 16x @ 3.0. This led me to realize my possible mistake of getting a CPU capable of only 16 pcie lanes. We are currently still using this system on a daily basis for our studio shows, but do notice the GPU overload still pop up from time to time.

current inputs are: 3 sdi inputs from quad 2 card, 2 external renders from the same quad 2 (only 1 quad card currently installed), 2 NDI inputs (ndi scan converter), 1 NDI output, 1-2 vmix calls, 6 audio inputs via focusrite audio interface. 2 audio outs (A and B routed to channels 5 and 6 on focusrite interface), 5 playlists (show intros, show assests, moving PIP backgrounds, studio TV backgrounds, and music beds), and maybe 2 multi-view sources. We are also currently using 1 full-screen hdmi output to send "output 4" to the monitor behind our talent. I will be checking tomorrow to see if this tv is same Refresh rate as our main VMIX program monitor in the control room.

I tested adding 10 full SDI sources yesterday for a future show (via decklink quad 2 and duo 2, gpu running 8x @ 2.2). I let it run for 16 hours and it seemed to be ok, but unsure of its stability as opening settings menu and others things seemed slower than normal and definitely was seeing way more GPU overload warnings.

All this to say, I have now pulled the trigger on building an X299 platform to try and get my SDI inputs back to 10 (with 2 sdi rendered outputs) and have my graphics card at full 16x 3.0 hoping to eliminate some GPU overload.

This is a more conservative build than I would have liked, but we're going test it against the z390 build: (hoping the x299 conservative build will offer more bang for the buck, the z390 build was a bit overkill I think)

MSI x299 gaming pro carbon ac Micro Atx (really wanted to do the EVGA x299 micro, but the MSI had 2 nics)
I7-7800x (hoping I don't regret this CPU - only 6 cores, lower clock, but trade off for 28 lanes)
MSI GTX 1070 mini Aero (wanted small form factor GPU, may upgrade later)
32gb ram ddr4 2666 (corsair)
970 evo 500gb NVME
2TB 860 Evo SSD
corsair h55 liquid cooler (may have to upgrade this to something more powerful but wanted to start smaller)
corsair cxm 550 80 bronze semi modular power supply
decklink quad 2
decklink duo 2 (as we move more and more into NDI, buying sparks and birddogs, we maybe change this to a 10GB nic instead to allow more NDI bandwidth)
focusrite 18i20 audio interface

If anyone has any thoughts I'd love to hear suggestions or comments, otherwise I'll keep everyone updated on how these systems compare. (parts come in Feb 15th for the X299 build, will start testing on the road the next 2 weeks at the Mary Nutter softball tournament in Palm Desert with a ton of NDI, and then the week after at The American rodeo semi finals in Ft. Worth Texas. We'll also be seeing how these machines stack up against our 3 HP Omen gaming laptops currently at a sprint car racing event in Florida, and at a track and field event in New Mexico next week.

x299 will be the only option for 2 or more capture cards, especially the Quad 2 which requires 2x x8 ports in addition to the graphics card.
This is not possible on z390 boards which generally have 2x x8 + 1x x4 and the x4 is shared with all other system peripherals so not recommended
for even a second x4 card.

Hope this helps.

Regards,

Martin
vMix

Here is a simplified breakdown of each chipset:

Z390: 16x CPU lanes + 4x Chipset lanes
(Generally divided up as 2x x8 ports, 1x x4 port with last x4 port shared with peripherals)

X299: (9000x series or higher): 44x CPU lanes + 4x Chipset lanes
(Generally divided up as 16x + 16x + 8x + 4x + 4x)

78xxx has only 28 pcie lanes which may lead to one or more slots on the motherboard physically disabled, so it is not recommended.
The newer 9800x does not have this limitation and is generally the same price.

And for today, whats the "best" X299 Mobo for vmix?

It won´t work for the i9 9900k, isn´t?