Well it definitely encoded a lot faster than it's doing now. I also notice by the preview window, it was displaying the video a lot faster than it's doing now.

I also had 100% GPU while using Adobe Media Encoder CC 2015. I don't like their subscription model which is why we went with Vegas.

An older driver may have worked a bit better but the GTX 950 is actually not well supported by Vegas Pro. Vegas uses OpenCL and not CUDA for timeline preview and some codecs, which why currently AMD cards are better for it, actually much better.
As for rendering. AMD cards render MPEG2 codes very fast, especially if the FX used is a Sony own FX or one that uses OpenCL too. CUDA rendering s only available for MC AVC and SONY AVC and only works for FERMI based Nvidia cards; GTX580 was the last one.

I figured I'd just reinstall the whole OS. I was getting strange lockups even is registry editor when I'd do a search, and it would crash.

So I reinstalled a fresh Win 10 64bit, all drivers from motherboard site and updated to latest nVidia drivers. Installed BlackMagic drivers and Vegas from the CD and selected to download and use the latest version.

It's still only using 40% GPU and Vegas crashed at 7% render, just locked up. I wish I still had my settings from the trial version, everything was stable and I was able to get through many renders while 'trialing' out the software. I guess it really wasn't a wise decision to purchase this program when I could have gotten tons of other programs to render using just the CPU. The 'main' purpose of buying Vegas was to capture live video with the option of editing and using the GPU to render as fast as possible (as stated in the product description). And then to use DVD Architect to burn the render to DVD as fast as possible.

Here's a screen shot of GPU-Z after it crashed:
http://s11.postimg.org/4dpcuukcj/Untitled.png

Vegas can do all of that just not with your video card. If you want the fastest render for Internet, a GTX580 or HD6970 is your best choice. Yes, these are old cards, rather easy to get on eBay but unfortunately these are the only ones that will support CUDA or rendering with OpenCL.

There thousands of threads around this issue.

It's strange how "Preferences-Video-GPU Acceleration" has my video card and I can select it, like it knows about my card and supports it. And then in "Render As-AVCHD-Customize Template-System-Check GPU" says "No GPU available". What a shame to have a card with a 6441 LuxMark, Open CL 1.2, & CUDA 8.0.5 and not be able to use it.

I'm not too versed in GPU computing, but it's hard for me to understand how Folding@Home, Seti@Home, & some SHA/WPA crackers can basically use any video card that's capable of OpenCL or CUDA. I thought these programming interfaces were supposed to eliminate the need for low-level video card knowledge.

[I]I thought these programming interfaces were supposed to eliminate the need for low-level video card knowledge.[/I]

Wouldn't we all wish for that.

It is not important how good your card is but how well the software has implemented it's use. When GPU acceleration was first introduced in version 11, the GTX580, which has a FERMI GPU, was the flagship. Nevertheless, CUDA was never implemented for timeline preview, only OpenCL. CUDA rendering was always only available for MC AVC and Sony AVC encoders. The reason you can see your card in the preferences is that your card is OpenCL capable, just not as good as an AMD R9 series.
The reason why you cant see it under rendering is that Nvidia has drastically changed the architecture after the 500 series but Vegas was never updated for newer cards. Even the R9 series doesn't do anything when it comes to rendering with MC ABV or Sony AVC when you select OpenCL, these two encoders where never updated to accept newer hardware. However, the timeline preview does work very well with the newer AMD cards. Unfortunately, Nvidia has not implemented OpenCL but rather went their own way with CUDA; there is some OpenCL capability but by far not as good as AMD.

How do think a GTX 580 or HD6970 would render compared to a Core i7-6700K 4.0GHz?

Again, it depends what you are rendering, which codec. MC AVC... .

Well, for right now we're making DVDs. We have a camera that outputs 1080i, so we capture that in an .MXF. Then we render that down to DVD quality MPEG-2. We may be doing other higher encodes in the future, or live streaming over the internet, but for now just sticking with DVDs. The videos can be about an hour and a half in length. But we may also use it for encoding weddings in the future too.

Adobe Media Encoder transcoded it to an MP4 or M2V in about 21 minutes. VP13 w/GPU wants to render at 34 minutes but crashes. VP13 w/CPU renders at 25 minutes. And somehow during the trial stage and installing/uninstalling multiple other video programs we were able to get VP13 stable while rendering to DVD at 13.5 minutes. I'd like to get that 13.5 back, but think it's impossible now.

We're trying to keep things simple for other people to follow a check list, which is why we're not going with Handbrake or other 3rd party programs. With VP13 we can simply click to record video, click to render down to MPEG-2, then click to burn to DVD.

It's sad that Vegas has to be 5 years behind in technology. What's Sony's beef with nVidia? They couldn't get a 4 year old graphics card to work in 4 years? Seems like they've stopped supporting Vegas and they're just trying to rake in the money now with old tech. Oh well. I guess I'll be stuck with CPU rendering due to their false advertising.

$600 Vegas Pro 13 System Requirements: (from their website)
"GPU-accelerated video processing and rendering requires an OpenCL™-supported NVIDIA®, AMD/ATI™, or Intel® GPU with 512MB memory; 1GB for 4K."

Look at the system requirements from the release notes of the current VP13 version. It still states that Nvida recommends a Fermi card. That has been conviniently been ommited from the actual product page. A HD6970 of eBay may be a better option in your case. It will render MC and Sony AVC with GPU support and also help with timeline performance. Those sell for under 100$ on eBay. Dont get a dual GPU card like the HD6990, it wont be any faster.

This is a new system I'm selling to a customer and I really don't want to put in a 5 year old used part.

Would a new Radeon R9 300 series work well for OpenCL? I'd rather stick to the $170-$230 price range since I only spent $140 for the GTX950. I've seen someone mention to get an R9 280, 280x, or 290, but still don't want to get stuck with used equipment I've heard that the 300 series is a rehash of the 200 series.

Yes it would with the limitations mentioned. No additional GPU render support for MC AVC and Sony AVC.

The R9 380x has been available for about a month. It's a modern and full implementation of a chip that has been around for a while. This one fits into the niche that you described.

An example here.

I don't own one, but have considered it.

Well, Nvidia 970 definitely works. I have rendered a number of tests and for example a 2 minute project, 2 clips with cross fade, color corrector and levels added to track FX: Render to MainConcept MP4 1080p, 2 passes;

Renders in 6:11 with Nvidia card turned on in preferences under video tab

Renders in 7:54 when acceleration set to off.

That's about 20% faster. It's not huge, but it adds up.

Wouldn't it be able to render okay with OpenCL MC AVC? There is an option in Encode Mode for "Render using OpenCL if available". If I have an AMD card with OpenCL, shouldn't that work?

I don't see that option for Sony AVC, which is fine as long as in the future when I'm ready for AVC encoding I'd have that option without VP crashing.

The MC AVC encoder is old and not written be SCS. It will look up the GPU model and only support those it was written for. So even if you can see the OpenCL option, if your card isnt supported it will revert back to CPU only without telling you.

So I figure it'd be pointless to get an R9 300 series. I took my R9 280x from home and tried it in this computer.

I got a 12038 LuxMark compared to the GTX 950 of 6441. But the render time was 48 minutes compared to the GTX's 34 minutes. GPU usage was only 22% compared to the GTX's 40%, but at least it did complete the full render without crashing.

MC AVC had no GPU load, and Sony AVC had about 23% load with little gains over the CPU. I guess my only options are live with CPU renders or sell a customer a new computer with a 5 year old used video card with who knows how much gain in performance over the 5 year newer CPU.

How much GPU is used depends on the codec, fx and source material. Try and render to XDCAM or a MPEG-2 like BluRay and you will see the difference compared to the GTX.