I've been using an Intel NUC 5i5ry for the past 6 months continuously with
Blue Iris, running 3 cams off of it, works extremely well, but one needs to do a fair amount of tweaking and tuning win7 64 to make it usable. It is not going to work right out of the box with just a basic win7 install and no tweaks.
Screen shot from the NUC:
And the BI screenshot:
As it stands, I'm running 2 wifi cams (the two top cams in the image above), and one wired cam (shop2 cam), all are running at 2.1MP @ 20fps. The three cams are being recorded to a generic usb3 external drive case with a 2tb WD purple drive. I am using an Intel 320 series SSD for my main drive.
Oh yeah, this machine is used only for Blue Iris and nothing else. I don't use it at all, and as you can see, I'm using TightVNC to even access the machine from my other computers in the house. As for acessing it outside of my network, I'm using IP Cam Viewer on my android phone to pull up realtime video from BI when I'm not home, it works quite well and haven't had any issues with the setup, other than a bad wifi cam several months ago (which is now the wired cam you see in the image above).
One thing I will say about this setup, BI refused to install as a 64 bit program, most likely due to me tweaking the os way too far! 32 bit BI is what I ended up running, and that's what you see in the image above.
I'm very happy with the way this thing runs, its cool, silent, small and mounts right to the back of an older monitor, so its out of sight, out of mind. Unless someone actually turns the monitor on, nobody knows that its the surveillance machine!