Blackmagic Forum

At this point, it is safe to assume most people know there are a few important points in your computer build. Things like which GPU, what CPU, and how much RAM you have. Well, I have found another bottleneck which was not even on my mind when I recently upgraded my system.

I first upgraded with a new hard drive because I needed a dedicated drive to video projects anyway. In addition, I upgraded from 32GB to 64GB of RAM (glad I didn't go all the way to 128GB...will explain later). These two points did help, but not enough.

I then decided to bite A bullet (more bullets were bitten later, ) and upgraded from my ald R9 290 to an RTX 3060ti. Generally speaking, the video upgrade was only noticeable during video editing. During picture or audio editing, the GPU upgrade had no noticeable impact. The system still couldn't keep up with the projects I was attempting to work on, one of them even approaching being unrecoverable due to immediately maxing the GPU memory and crashing DR before anything could be done.

And thus, the second bullet was bitten... I upgraded to an RTX 3090ti. Again, in general, no difference to system operation, web surfing, picture or audio editing, etc...from the R9 290. In DR though, In DR, totally different story. Things went from being inaccessible to working nicely again.

Here is where the useful part comes in. I started noticing...no matter what, projects were still laggy. I kept an eye on the performance tab in the windows task manager to try and spot where the bottleneck was. The hard drive almost never registered activity...so that was ruled out. I had plenty of available RAM...so that was not it. The CPU was only registering 30-40% usage...so that wasn't it. The GPU had plenty of overhead, registering between 15-40% usage, plus VRAM only registering about 50% usage.

So what the heck was the bottleneck? Turns out, the bottleneck is my motherboard. As of this current time, it is now 2 standards old for the PCIE bus. My motherboard can't handle the data throughput. That's nice and all but...How can this help you?

Well, if you are noticing your projects are laggy, but nothing is near being maxed out (RAM, storage, GPU, CPU), it is possibly your motherboard that is bottle-necking your system. My mobo has PCIE v3. You may need a mobo with a newer standard of PCIE interface.

Hope this helps you, at the very least, identify a possible motherboard bottleneck before you end up spending a bunch of money on other stuff that won't fix the problem.

If your motherboard have PCIe3 i don't think it is the bottleneck.

Did you checked the power profiles of Nvidia in Nvidia Settings and the overall power profile of your system?

Alex Silva wrote:If your motherboard have PCIe3 i don't think it is the bottleneck.

Did you checked the power profiles of Nvidia in Nvidia Settings and the overall power profile of your system?

Yep. All set to maximum performance. AND...I see the exact same thing in Particle Illusion. It doesn't touch the hard drive, memory has lots of headroom available in both RAM and VRAM, CPU ticks in around 33%, GPU ticks in around 33%. I even tried to run some other applications concurrently to see how it would affect the renders. The other applications would stall out heavily, but the CPU and GPU usage would stay pretty much the same...with no adverse affect on the render times. It is a data-bandwidth bottleneck in the system. The motherboard is really the only component I haven't attempted to update.

And, after looking into it, I also can't. I would need to build a new computer entirely. Well...not entirely. The mobo and CPU would have to be replaced, which would require the RAM and PSU to also need to be replaced. Everything else could transfer over.

I wonder if it's more about PCIe lanes than version.

A lot of mobo's only have 20, and that GPU will take 16 of them, leaving not enough for other things.

Maybe a board with 48 lanes would help here?

That is why I got a Threadripper several years ago. Not great for performance now but at least I see the CPU at 100% and my 1080Ti in the 90% range. But of course for decode of h265 it is the CPU maxed out as it is a PCIe 3 board of course and 1080Ti does not decode my GH6 files. Have the Studio Max for now but may go back to PC upgrade next year.

Jim Simon wrote:I wonder if it's more about PCIe lanes than version.

A lot of mobo's only have 20, and that GPU will take 16 of them, leaving not enough for other things.

Maybe a board with 48 lanes would help here?

I am glad you mentioned this. I made an assumption here, and I think the culprit might actually be my CPU. On a whim, I decided to verify my board actually did only have 28 lanes. Turns out it is my CPU that only supports 28 lanes, while my mobo supports 40. I may try upgrading to an i7-5930k or i7-5960x since they both support 40 lanes.

(insert about an hour time-lapse here) {optical flow & speed warp activated}

So, I just ordered an i7-6950X. Moving up from 28 lanes to 40 lanes, and 6 cores to 10 cores. Will be a slight loss in GHz (-0.3GHz) from the i7-5820k. But, that's a minor change even for just single-core comparison. The extra lanes should help with the bandwidth bottleneck, and the extra 4 cores will definitely help.

I am currently having issues with a 4kUHD project that is 30 mins in length. It has been getting to almost 50 seconds worth of 24fps into the render and crashes DR cold. Suddenly shutdown with no recovery possible. The last attempt showed the projected render time peaking over 3 days, 9 hours. What I am currently working on is breaking the fusion comp into a bunch of tiny fragments to render and then comp those together in the edit page. Unfortunately, that puts me having to deal with giant DNxHR files. I must have the alpha channels...and I don't want to deal with compression artifacts well before the final render is even ready. It's been annoying to say the least. That said, I have learned a HUGE amount about Fusion.

And, I have come to the conclusion that I hate the Particle Illusion software's interface. Yeah, sure...it can do some awesome stuff with particles. I dislike it enough that I scrapped nearly all the particle ideas I wanted to do. Someone really needs to create something similar to Particle Illusion that works natively inside Fusion. I would actually pay real money for something like that.

Anyway...back to the original topic. I should have the CPU installed in a few weeks. I will report back here with an update...on the off chance there is someone else out there dealing with something similar...and this ends up helping.

"Suddenly shutdown with no recovery possible."
Only DR or your machine? If the latter, you may have to think about your PSU.

Uli Plank wrote:"Suddenly shutdown with no recovery possible."
Only DR or your machine? If the latter, you may have to think about your PSU.

It was just DR. Nothing else was affected on my system.

AnthonyReno wrote:What I am currently working on is breaking the fusion comp into a bunch of tiny fragments to render and then comp those together in the edit page.

Would Cache help here? Using it for export?

Jim Simon wrote:

AnthonyReno wrote:What I am currently working on is breaking the fusion comp into a bunch of tiny fragments to render and then comp those together in the edit page.

Would Cache help here? Using it for export?

It probably would, but I am not willing to wait 3.5 days for it to cache.

Well, it's gonna take the same amount of time to render - whether it's Cache, Render in Place, or export.

Jim Simon wrote:Well, it's gonna take the same amount of time to render - whether it's Cache, Render in Place, or export.

What I am currently doing is simply breaking the fusion comp into a bunch of small segments, then rendering each of those smaller segments to a DNxHR file. So far...I am able to get the renders to complete successfully. The current clip is rendering out at a whopping 0.5fps...for a 30 minute clip [timeline is 24fps].

For this current pass, the CPU has been mostly idle, while the GPU has been spiking to 100% usage in pulses. I may be reading this incorrectly, but that seems to indicate the GPU isn't being supplied with data fast enough to allow it to maintain a constant grind.

I'm going to need to do this maybe 10 times to break out the layers sufficiently so I can re-comp them in the edit page.

I received my CPU way faster than expected. I already have it installed, and did a quick test on this project which has been causing me so much trouble. Night and day difference. Previously, the project would take about 4-5 seconds per frame for playback. Now, I saw a playback speed of as much as 6fps! And, in the performance tab (task manager) the overall CPU usage was being reported as less, as was the overall GPU usage. Granted, we aren't talking a huge difference. The differences being reported were only a few %, but still...a net drop overall. Thus, the bottleneck was definitely data-throughput.

So...if you are having issues with system performance, have upgraded your GPU, RAM, storage, etc...but are still getting serious lag...it could be a data bandwidth restriction. In my case, it was the CPU that restricted the data bandwidth. Hopefully this helps someone!

Nice, What are the movie specs that is playing at 6fps in your system and what edits have you made to it?

Alex Silva wrote:Nice, What are the movie specs that is playing at 6fps in your system and what edits have you made to it?

4kUHD @24fps. As for the edits...it's much easier to just show the fusion node tree.

Aha!