Motherfucker. What a week.

My computer (including two hard drives) died few days before new year and I had to buy a new one right away. Which meant I didn't have enough money to buy certain parts what I really wanted and I had to make some "sacrifices" on motherboard and CPU. Meaning after over ten years of journey together, I had to say goodbye to AMD and say hello again to Intel.

Few days later I got all the parts and when I install everything back to normal (OS, programs, etc), it usually takes two days of installing stuff and tweaking settings. Did that and week later third HDD died. Luckily I managed to get everything I needed to safe before it finally crashed and burned. I replaced the HDD and I thought everything was in right place. Then I started to notice that my new computer had some latency problem with the audio. Annoying sound clipping and pops was here and there whenever I played music on Winamp and it only started to appear after the computer was on atleast 24 hours. Fucking weird.

I still use old Soundblaster X-Fi in PCI-slot and I'm not planning to buy new one. Why should I? As a 24bit soundcard it still works fine and I have carried that thing over from my two previous computers. So I thought it was a driver issue, as usually. I mean, Creative have a track record making either shitty drivers or software. Or if you're lucky, you'll get both when you buy a new soundcard fom Creative and you have to wait for proper drivers to arrive. I tested every driver there was - for LAN, motherboard, graphics card and I noticed that even Creative managed to release new drivers for good old SB X-Fi in last year. So yeah, I tested everything and nothing worked. Even updating the BIOS didn't do anything. Same annoying clipping appeared.

I was getting a bit desperate and started looking for solution from the bottomless pit called Google. Hundreds of search results with similar problems and usually it was Realtek audiochip from motherboard giving the headache. That didn't help with my case. Search after search, I stumbled on a program called LatencyMon. It's a program that tells which process, driver etc. is causing this latency. Hooray, atleast we were on right path on this troubleshooting.

And it even suggested what was causing this. So with more trial and error approach, I changed some BIOS settings related to CPU power management. I mainly disabled "Enhanced Intel SpeedStep Technology" and then I went to Power Options in Windows 7 and selected "High Performance". That was it. Everything was back to normal. Also it doesn't hurt to set processor scheduling to "Background services" in system settings (Computer --> Properties --> Advanced system settings --> Performance --> Advance --> Select "Background services").

tldr; Just disable your power management from BIOS and OS and your audio stops clipping.

Edited two weeks later: Well... The initial problem was only masking the true problem. DPC latency was still there but now it took atleast two days to kick it in full gear. Still tried every available fixes - from countless registry tweakings to trying again different driver preferences. Then I finally found this forum post.

Yeah, when I bought the new computer, my Avast license was also expiring and I decided to upgrade Avast antivirus to Internet Security because my father's laptop needs full protection (sometimes from himself). Because I use a bit advanced firewall in my system, I only needed the antivirus so I disabled the firewall etc. from main program and I thought that was it. Wrong, wrong, wrong. Apparently it's still someway active and creates these nasty spikes in DPC latency. So you need to uninstall the firewall part completely from Avast (Control Panel --> Programs And Features --> Avast Internet Security --> Change --> unchecked the firewall feature and restart) and that's it. The headache is finally gone.