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Sound stopping and starting - GPU bottleneck?

Posted: Mon Mar 06, 2023 1:51 pm
by technodevotee
Sorry about the length of this post but I need to give some background to the problem I am facing.

I have been using WMC since it came out and have run it on all sorts of PCs with very few issues. I have always found that it performs very well but I am somewhat stumped by what I encountered recently as it is outside my experience.

My current home brew HTPC comprises of a Gigabyte z370 HD3 Mainboard, Intel i7-8700k 3.7GHz (6 cores), 32GB Corsair Vengeance LPX 3ghz RAM, 1TB Samsung 970 EVO PLUS M.2, PCIe NVMe SSD and four Hauppauge WinTV Starburst 2 DVB-S2 PCIe cards. It runs Windows 10 and am using the on board Intel Graphics.

It is a few years old but works fine as a general purpose Living Room and Windows Media Center PC.

However, my wife got interested in using X-Plane but obviously the HTPC is not much cop for playing games and the like - especially not something so demanding.

At this point, I should say that our only experience of games has been a DOS pinball game back in the 90s, MS Flight Simulator back around 2010 and low end stuff like Solitaire and Jigsaw puzzles. Safe to say that, as a retired Computer Engineer who worked on Mini Computers, High End Servers and business PCs, the world of gaming is completely alien to me.

Anyway, I have two other PCs that were built for number crunching. They both have the same spec, which is 750W PSU, ASUS® PRIME X299-A II: ATX Motherboard, Intel® Core™ i9 12 Core Processor i9-10920X (3.5GHz), 16GB Corsair VENGEANCE LPX DDR4 3000MHz (4 x 4GB in quad channel mode), 4GB AMD RADEON™ RX 550 - HDMI, DVI - DX®, DP Graphics Card, 1TB SAMSUNG 970 EVO PLUS M.2, PCIe NVMe SSD.

So, I decided to install the trial version of X-Plane 12 on one of those to try it out and was appalled at how slow it was. It was so slow that X-Plane kept telling me to reduce the resolution from 1920x1080. I then installed FSX and was equally appalled at how slow it was compared to how it was on the lowly PC I’d used it on years ago.

At some stage of the investigation, I had the PC hooked up to the AV Amp and, therefore, the TV in the Living Room and was playing some recorded TV in WMC.

Finally, we get to the subject of the post.

When I played a recording of the Vienna New Years Concert on it, I was horrified to find that the Sound was breaking up and stopping when there was a lot of action in the picture. The same recording has flawlessly glorious surround sound when played on the HTPC. I have since tried the same recording on the other identical PC as well as some other recordings, with the same results.

I assume that the problem with WMC is a result of the same thing that makes the games I tried so bad.

I have since read that one has to match the GPU to the CPU and it seems that suitable cards would cost in the region of £300-450 apiece. I ran some tests and they seem to confirm that, even though the cards in the PCs are not terrible per se, the throughput of the GPU is too low to keep pace with the processor’s ability to throw stuff at it and is causing a GPU bottle neck, which would explain why the GPU utilisation jumps between 0% and 100% while the CPU is almost idle most of the time.

Unsurprising, I am reluctant to shell out that sort of money so that they can run WMC (and so my wife can use X-Plane 12 until she gets bored with it) as these PCs are rarely used nowadays.

Are there any Gamers on the forum that can confirm what I have read is correct?

Re: Sound stopping and starting - GPU bottleneck?

Posted: Mon Mar 06, 2023 2:29 pm
by technodevotee
I should add that the i9 PCs are running Windows 11 and have had WMC installed on them for a while as they have DVB-T2 Tuners and act as backup recording devices.

However, I rarely play recorded TV or any kind of video on them as they are in my 'office' and, because there's no Surround Sound from terrestrial TV when recorded on WMC in the UK and no Surround Sound system attached, I would probably never have encountered this problem before.

As a test, I did a fresh installation of Windows 10 on a spare drive, installed all required drivers and patches, then installed WMC and connected up to the AV Amp and TV. I found that the results were the same as before - give or take.

Re: Sound stopping and starting - GPU bottleneck?

Posted: Wed Mar 15, 2023 11:58 am
by technodevotee
I've been doing some more research on CPU-GPU matching to avoid bottlenecks and found a calculator on which seems to support what I've read so far.

It appears to confirm that an ideal match for my i9 10920X would be something like the AMD Radeo RX6700 xt, which can be had for about £400.

I have no idea whether that would fix the problem with WMC so I am reluctant to buy one.

What is weird to me is that my i9 10920x is apparently 'too weak' to run even MS Flight Simulator at anything over 800x600 with that card.

Well I'm sorry but that is nuts. Looks like I can forget gaming or running WMC on these PCs.