For any drop-outs from Glitching-on-Sea and Crackling-over-Speighkers

[jabe]

I’m putting this on here in case it proves useful to anyone suffering from glitches, crackles, drop-outs, etc. It’s a bit long, but I hope it’s informative and helpful.

I’ve been given an old Windows XP PC. I’m going to use it now and then to juggle files around on my seven external hard drives and my NAS drive. I’ve added two four-port USB cards.

I reinstalled XP after finding out too late that the Avira Free installer exe (the 4MB one) doesn’t work at all, for anybody. I mistook it for a problem on the PC.
No matter, I now have a new install and the hard drive is NTFS format instead of FAT32. SP3 is on, along with a ton of other updates. The CPU is a 1.7GHz AMD one. Not fast, but it should be do what I want.

Now then, when it was turned on and doing nothing at all, the CPU% was around 18-25%. And that offends me greatly. I’ve had problems with Interrupts hogging CPU time on other PCs. The previous one occurred because using the Sleep/Hibernate mode too often caused XP to change the hard drive access mode. Once I knew that, I was able to reset it, and noted the solution for future recurrences.

This time I launched Process Explorer (ProcExp from the splendid Sysinternals Suite). It has a line for Interrupts third from the top as the first entry within System. The process is called Interrupts and the Description says “Hardware Interrupts and DPCs”. It was jumping around the 20% mark.

I did some Googling about Interrupts and DPCs and the concensus was that an excess of either would results in disruptions to all streams of data, since the CPU gives priority to dealing with both rather than to any programs that are running. I tried running PerfMon from the DOS prompt, adding various interrupt and DPC graphs to the display. The DPC ones were a little contradictory, but one of the lines looked as if it meant trouble. I then found a program called DPC Latency Checker on www.thesycon.de. I’m not sure how useful it was, but it did show that my DPCs were constantly in the red (and still are) and it said this was down to poorly performing drivers. It suggested disabling hardware devices one at a time within Device Manager (via either Control Panel/System, Hardware tab, or right-click (My) Computer to get Properties, then Device Manager and Hardware tab).

I almost always have Task Manager running. Its CPU graph was jumping around the 20% mark (though oddly the System Idle value under Processes was showing 96/98% most of the time).

I disabled and re-enabled several non-vital devices. Don’t do the CPU, the hard drive with your operating system on, the display/graphics card, the keyboard, mouse, etc. Hope to heck that it’s not one of those. If you have another graphics adaptor you could use - perhaps the one on the motherboard instead of the graphics card - see if changing it makes a difference.

It might be that something you’ve disabled requires a reboot for it to be properly re-enabled. Mine did for the network card. It might be that you have to reboot in safe mode (boot and keep hitting F8, then choose Start Windows in Safe Mode). I didn’t have to do this.

The PC has two USB sockets at the front of the case and two on the motherboard. Disabling two of them – the ones on the front, I believe – made the Interrupts/DPC usage drop. In ProcMon it changed to <0.01% and on Task Manager the CPU% became 0-2%. Sorted.

If you uninstall a device via Device Manager (using right-click, etc), Windows will generally try to reinstall it when you next boot up. Oddly, when I rebooted, the USB sockets were re-enabled, but the Interrupts usage stayed low. I don’t know why.

Meanwhile, it turned out that one of my USB cards didn’t work at all, so I shall get a replacement.

[chico.co.uk]

You want to have a look at this too. Specifically the drivers tab. Leave it running for a while, then order it by "Highest execution" in m/s, and also DPC count, to try to track down any potentially "iffy" drivers that are causing pops and crackles.

http://www.resplendence.com/latencymon

[jabe]

Good one!

[chico.co.uk]

I've just been rebuilding a laptop (which will be on windows 8.1) and I'm cautiously optimistic that I've finally made some tweaks that might get rid of the pops and crackle type issues I've always been plagued with, across multiple machines, for years.

Latencymon has definitely helped suggest things to look at. Disabling the wifi card seems to have made a massive difference, at least on that machine, (after noticing that ndis.sys and tcpip.sys generated either a load of DPC calls, and high execution times, in microseconds). Some info here was worth reading;

http://www.sweetwater.com/sweetcare/art ... cy-issues/

And i think the PC optimizations suggested on the links off here look useful;

http://www.sweetwater.com/sweetcare/mac ... imization/

I don't think LatencyMon actually works on XP though, i'm afraid ...

[jabe]

I'll check your links later, but one option I'll be using for mine is to have batch files that can stop (a) selected processes and (b) selected services running. I will run them after my PC has booted. They'll stop the internet and the antivirus too, so as little as possible is running. The advantage of doing it this way means that if a process or service shouldn't have been stopped, a reboot will bring it back, and the batch file can be edited to reflect it. There are easy ways to tip lists of all processes or all services into a text file for easy editing into batch files.