Tower T3620 - Intermittent Hdmi sound crackle

Motherboard doesn't have built in graphics.  It's built in the CPU.  CPU still works with a GPU card.

Try removing GPU card and use onboard HDMI and see what it does.  I'm not too optimistic because I also have a 3620.  If my monitor is connected to onboard HDMI, it goes black every few minutes and comes back on.  (2 different monitors.)  I have to use DP.

You might want to try a different GPU card before chalking it up to the MB.  That's just in case there's any compatibility issues with the RX470.  Do you have the latest driver for the RX470?

Yes, an aftermarket MB will fit in the case.  But there's the big however.  However, everything Dell does is proprietary.  Wiring is proprietary.  Screw standoff placement is proprietary.  And then there's the rear panel.

The PSU* uses 8-pin + 4-pin connection to the MB.  One can't go from 8-pin (PSU side) to 24-pin (MB side).  24-pin being an aftermarket MB.  With an adapter, one can go from 24-pin (PSU side) to 8-pin (MB side); but that's irrelevant to your 3620 unless changing to an aftermarket PSU.  In other words, aftermarket MB would need aftermarket PSU.  *If I remember right from past posts, you have the 365w PSU.

Do you game with the 3620 or what is it basically used for?  May be there's some GPU card settings that can be tweaked.

Thank you for your quick reply.

I was wondering if the graphics part of the cpu was at fault.

And the motherboard was another possibility, but no, it seems my Linux operating system didn't like the HDMI / DP.

So I found new drivers on the AMD website for my 8gb RX480 and now there is no sound at all. Thank you AMD :( 

I have had a 4gb Nvidia sitting on my shelf for years, the hdmi sound isn't even detected by Linux, so I'll go to Gigabite and look for drivers for that. 

In the meantime I have installed a well old Radeon HD4770 (that I meant to throw away), and the hdmi sound seems to be behaving it's self. All be it an awful card in every way.

Thanks again for your help and advice, I'm off to get drivers or a new graphics card :)  

I think you meant the "RX470" and not "RX480"?

What I meant by tweaking GPU card settings was perhaps lowering FPS and see if that helps.  I'm not 100% sure that's it, but it's a try.

Yes sorry I meant rx470   :)  

My other rx470 turns out to be a rx570, I had to use a magnifying glass to read the tiny sticker.

The Radeon HD4770 worked for a while then back to the crackles.

So it can't be the graphic cards, or FPS as the rx470 & rx570 will no doubt have a higher FPS. 

I have used two cables Dp and HDMI, and two monitors, so we can rule those out.

So that narrows it down.

I have asked the guys at Linux, but no joy so far. 

It worked well last night for a good eight hours, this morning worked well, then I got my email and then the crackle came back. Could just be a coincidence. 

Yesterday I noticed that after a re boot it went away.     

No not yet, but a pattern is emerging, just after boot up the crackles start, then after a re boot all is well.

The first thing I do after boot up is open Thunderbird and look at my emails, so tomorrow I'm going to boot up and leave Thunderbird alone and see what happens. It might be nothing, but maybe. 

I'll try without a gpu card tomorrow if all else fails.

A motherboard or a bear bones tower doesn't cost too much on ebay, I sort it when I tire of rebooting :)   

If you do have to get a used/returb MB, I'd shy away from getting a barebones PC.  And it's probably not guaranteed to work.  Sometimes I see in this forum some people have a hard time getting them going.

Also, if you do anything in relation to that, stick a new battery in the MB.  I had to replace the battery upon receiving every refurb PC I ever bought.  Sellers don't check the battery.