I have recently purchased Diablo 3 and noticed that the sound in the cinematics of that game was out of sync and always a few seconds behind the visual and the subtitle.

I then read that overclocking of the CPU can cause that. As I usualy run my 3Ghz 960T at 4.2Ghz I decided to re-set it to the 3Ghz default.

The sound was now in sync again with the cinematic and subtitles in the game. All fixed.

  • Why does overclocking the CPU affect the synchronicity between the cinematic and the sound?
  • How come it does not effect cinematics in all games but only some (Diablo 3 being the first in my case)?
  • 2
    Speculation: Whatever video or audio codec they are using is reading the chip's native clock speed for some reason, and is calculating some durations based on that
    – Nevir
    May 21, 2012 at 17:55
  • @Nevir: I know it is not an issue if I stay at default clock speed but was just curious as to why clock speed would matter. Your comment would explain the exhibited behaviour alright. I wonder if Blizzard is using something custom written to stream the cinematics as I would have assumed a commercial streamer (or what ever you may call it) would not be causing synchronicity issues with sound and picture due to over-clocking. Well, it is not a field I'm familiar with so I don't know any better anyway :)
    – Nope
    May 21, 2012 at 18:43
  • Let's see if gaming.stackexchange.com/questions/68597/… helps narrow it down
    – Nevir
    May 21, 2012 at 18:45
  • Is this a heat issue? My CPU is overclocked to 4.0ghz and has no problem with cutscenes.
    – Resorath
    May 23, 2012 at 20:23
  • @Resorath: Not sure if it is heat related but could well be. Blizzard recommends not overclocking the CPU to fix those sync issues so it seems to be a standard fix. My temps are just under 30 degrees. I have a massive dual-fan with copper rails on top of the CPU. Even when unlocking the additional 2 cores making it a 1060T 6 core CPU running at 4.2ghz it runs just under 35 degrees. I also don't have any issues with any other game's cinematics but again that does not mean it is not heat related off course.
    – Nope
    May 23, 2012 at 20:39

2 Answers 2


I have my I5-2500k OC'd to 4.5 Ghz. Your problem could have more to do with AMD specifically if it is indeed the processor that is the root of the issue. Is your machine a pre-built? I know that many pre-builts are not meant to be overclocked and the Power Supplies supplied are already at a ceiling.

I am assuming that this problem is only happening with Diablo 3. If not, then I would even go so far as to say there is an issue with your motherboard. Try to look up the model number and download all up to date drivers from the manufacturers website. Also, do the same for any discete graphics cards and your processor itself.

If the problems persist, please post back and I can try to suggest something further.

  • Thanks for the feedback. I upgraded a pre-build I bought in PC World a few years ago. I bought a new Gigabit mobo, 4gigs of matching dual channel RAM, new AMD 960T CPU, new dual-fan for CPU and new HD 6850 GPU. I had no issues when adding all the parts together and the sync issues only happens with this specific game. No other game shows that problem. It seems to be a well known issue as blizzard themselfes have posted on their forums that overclocking your CPU can cause this issue. Why it happens though is something blizzard has not said.
    – Nope
    May 29, 2012 at 16:10
  • However, it could still be AMD related off course, but without blizzard giving up some more info its hard to figure out :) I also only upgraded my drivers to latest last night but haven't played D3 since then OCed. Will try when I get home and let you know :)
    – Nope
    May 29, 2012 at 16:12
  • Definitely, your PC isn't stock anymore :-) Are there any error logs? It still has the potential to be a driver-related issue. Also, it may not be the audio that is out of sync, but the video. (unless it sounds like it is degraded in quality) May 29, 2012 at 16:15
  • Could well be. The video and sound do not seem to stotter they just don't start at the same time. It's like the sounds either starts a second after the video or the video starts a second to fast before the sound. This is an issue with a lot of D3 players but you could be completly right and it is unique to OC'd AMD CPUs. :)
    – Nope
    May 29, 2012 at 16:17
  • Have you noticed any other abnormally dark or blurry text? Anything that could attribute to a video card issue? Or possibly if you have a compatible video card laying around to test? May 29, 2012 at 16:26

This is not a professional answer however logically I think its one of these

  1. You sound card can not handle the increased data traffic slowing the onboard sound processor.

  2. You are need the max power draw and with a overclocked CPU its drawing power from the sound card.

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