What setup do I need to record and render at the same time? I need help figuring out how to record while my computer is rendering.

I am very new to video editing, so this is my current workflow.  First, I record footage using Fraps (30 fps, 1080p, .avi). I usually get several hours worth.  Then I use Adobe Premiere CC and Media Encoder to cut the video into 20 minutes chunks. I queue all the videos up in Media Encoder (h.264, mp4, 1080p, 30fps).

Each video takes about 30 minutes to render (intel 2600k. dual amd 6950s, 16 gb ram). My source video is on a 2 TB HDD and the destination is a separate 1 TB HDD.

Here is my problem.  While rendering, the computer can't be used for much else since my CPU usage is capped.  My GPU doesn't seem to be used at all (as I understand, h.264 encoding is almost all CPU based).

How can I change my setup so that I can record more video while the machine is rendering away? In addition to my PC, I have a NAS available, a Macbook Retina Pro (2012, 16gb ram), and two external HDD cages. I think I need to come up with a setup where I can record on one machine and render with the other, but I don't know if this is viable or which HDD to record video to in that situation (is recording to NAS common? or do I make the other computer's HDD a share drive? record to external drive and move it around?) 

There are a lot of unknowns for me here and I would just like to know what a "normal" setup is for using one computer to record and another to render.  I am on a gigabit LAN with my NAS and laptop, but the laptop only has wireless connectivity.

I would just render my videos over-night, but that is when I upload to Youtube, as that takes many hours.
I assume you record video game footage?
Recording and rendering on one machine is something I wouldn't recommend with a regular PC if you play modern games that take a lot of your CPU and GPU resources.

I usually recommend getting an SSD but in this case it seems you are heavily CPU limited.
You could theoretically encode on the GPU but I'm not sure if that will ease the workload all that much to be able to play games as you need your GPU to play games aswell and usually GPU encoding produces worse results than CPU encoding because of the way the codec is implemented for GPU encoding.

What I would do in your case is either render on your MacBook, rendering over the network shouldn't be too bad in this case as your MacBook will be CPU limited aswell.
Or you don't do the final encode of your videos with Premiere/AME but use a different h264 encoder called x264 which is a LOT easier on the CPU and with the right settings could potentially used while you play games. x264 is by far the fastest and most efficient h264 encoder today.

You would first render your cut videos in a lossless codec that doesn't takes very little CPU usage but be sure to not render to the disk that your game runs on, as a lossless codec will be very I/O heavy.

Alternatively if all you do is cut your videos in to 20 min pieces without any other creative decisions other than splitting up your videos at every 20min interval you could automate everything and ditch Premiere all together and just use FFmpeg which also integrates x264 so you can cut your videos automatically there and encode to h264 all at the same time.

You could theoretically also upload automatically after rendering if you are bit into programming and do all at night without supervising anything. That would free your pc up for recording during day. That can of course only work if you don't already need all night to upload the encoded videos.

There might be more viable solutions to your problems but that would need a bit more info from you. What do you record? What are you doing in Premiere exactly to the videos other than cutting? What are the specs of your computer?