First post, by Gemini000
- Rank
- l33t
OK, so I've been running DOSBox on my Win8 system for a little over a month now. For the most part, I haven't run into too many issues, save for DDraw mode not working nicely due to Microsoft depreciating the heck out of it, so I've had to swtich over to OpenGL and avoid using any graphics shaders that require DDraw. :P
However, recently when I was trying out games using the "max" cycles setting, I ran into what I thought were very strange framerate issues where it seemed to constantly fluctuate between high framerates and lower framerates. This was only happening with games I hadn't yet played so I didn't think anything of it and just set fixed cycles counts to get around it.
However, upon playing some games I had working perfectly fine with max cycles on my old WinXP system, I discovered the same problems, and after testing some things out I realized this wasn't actually a framerate problem, the emulation speed itself is fluctuating! o_O;
It kind of oscillates, going faster in some moments and slower in others, and switching between these extremes once or twice per second. What's odd is that this is only a visual problem. IE: The game is still playing at the correct speed and audio is still playing at the correct speed, but each frame seems to be staying on screen longer than it's supposed to and in order to catch up once there's some backlog, a number of frames are drawn and pass faster than they're supposed to. (I don't think it's related to 320x200's 70 Hz compared to LCD monitor 60 Hz considering this also happens with 640x480 resolution games.)
I'm also encountering random game crashes with games that NEVER crash (like OMF2097), thanks to divide overflow errors and I think it's related to this problem.
I should also note that lowering the % emulation speed does not solve this issue. Setting a fixed cycles count does, but is inconvenient for any game that should be working best with max cycles, since you have to swap between low cycles and high cycles depending on what's going on and can play havoc with joystick calibration.
Basic System Specs:
* AMD FX-8350 8-Core CPU @ 4.00 GHz
* GeForce GTX 660 GPU /w 2 GB RAM
* 16GB RAM
* Windows 8 Pro 64-bit
All of my drivers for the BIOS, Windows, GPU, CPU, etc., are up to date. It's also interesting to note that no matter what game I'm playing with max cycles, the CPU core DOSBox is using never hits 100% usage. Not even close. The highest I've seen for a single core with DOSBox with a game set to max cycles is 75%.
I would almost call this a graphics driver problem, if not for the fact that setting a fixed cycles count solves the problem, so I'm leaning towards something else, probably CPU or Win8 related... maybe both since I've been having similar problems with Flash. (Though those problems went away by disabling power saving settings in the BIOS, whereas my DOSBox problems are not affected by those BIOS settings.)
--- Kris Asick (Gemini)
--- Pixelmusement Website: www.pixelships.com
--- Ancient DOS Games Webshow: www.pixelships.com/adg
