To have a sufficient GPU is important to get vMix working smoothly. Which one depends on the most important question "what do you want to do with vMix?"
How many camera inputs and what input devices are you going to use?
Which format do you want to use for your recordings?
What amount of money is budget in your case/opinion? When you compare a vMix system to a broadcast level setup when it comes to features, a high-end setup is still budget if you compare it to other systems. In most cases you would have to add a zero to the right of the figure.

The CPU is important for things like NDI, recording, multicorder and replay. What do you need of those options and what options do you need at the same time, with how many inputs?

In general my recommendation is getting a system with a 40-lane socket 2011-3 cpu with at much cores you can afford with turbo speeds around 3Ghz.
16 GB of memory, with a Geforce 970 or up and SSD storage, will give you a nice system you can ask quite a lot of.

As a budget system for 4 camera inputs, a system with a Intel Quad Core CPU with Iris Pro Graphics, will already work well without a dedicated video card, as you can see in the specs of their vMix U.

To get the best recommendation for your usage, you need to specify as good as you can what you would expect to be able to do with the system.

As usual, YMMV. I think Mathijs' point is well taken. Whether CPU or GPU is more important depends upon which features you use.

I have a desktop running Windows 10 on AMD FX6100 CPU (3 core, 6 thread) with 10 GB RAM, AMD Radeon HD7400 GPU....it's running on 4 years old now. It handles my needs at 720p30...but only just.

In my case I need a faster CPU to be able to run vMix and a Hangout at the same time. I know that I can't stream and record to disk, even though my disk is an SSD.

If I were doing more layering I expect that I'd want a faster GPU.

You can set the delay on your sound input settings to get your external audio in sync.

A Geforce 610 is old and the most budget range of nvidia. You need midrange as a minimum.
I would advice a 650 as minimum spec. (more than 4 times faster than a 610)
Iris Pro Graphics on-board video is still 15% faster than a GF650.

I cannot give you a definite "yes", because I do not own a 650.
I have a 670 in one of my systems, and that does the job fine with nvenc on two encodings at HD resolutions. A 670 is more than twice as fast as a 650.
Every 6XX card under a 650 is a re-branded card of an earlier generation. The GeForce GT 610 card is a rebranded GeForce GT 520 and has no nvenc support.
I would expect it is no problem, especially at SD resolutions.

It's supported from Kepler architecture and up, so GF 650 is the oldest card supporting it.

Sure, if they have to buy a card, I would also get a newer series. TBH, I would not buy less than a 4GB 960 myself.

What i5 processor is in your system?

I've got a system (i7 2600K, 8GB) with a GeForce GTX 610 and have used up to 3 720p sources without issues.

For definitive answers on what GPU to select and how it would perform, don't re-invent the wheel. Instead see what the experts at vMix have to say: http://www.vmix.com/soft.../supported-hardware.aspx

- Tom

I looked at the video....it is jerky, and for what you did, it should be much better.....maybe the drivers for the PCTV cards need updating, ......try removing 2 of the cards, and try them one by one, just in case there is one that is giving problems, or maybe they do not preform well together....I have in a system, an Osprey 440 four input card, and so far, I do not have any issues......I also used 3 capture dongles, no problems...and my system is just a core 2 with 2 gigs of ram....so try using one card at a time, and add to see if one of your cards is not working well.....

it's an idea i was thinking about ....

2nd monitor for the studio feedback and local recording ..... it's definitly a good point.

Today i got my gtx 960 (asus strix) and seems a little beter performing.
Also i messed with the pctv drivers but cannot replace the "generic" bt868 drivers (maybe because one of the3 cards is a chinese pctv clone).

but at the moment seems i got the delay on external, but no gerky output.

yes external was a need because we made some shows LIVE on TV and the encoder needs svhs video (in the future i plan to connect dvb encoder and main studio with an IP link ).

thanks for the help.

Federico