Overclocking
Overclocking is the process by which the CPU clockspeed is increased. The reason for doing this would be to reduce slowdown in games, or to increase the framerate. However, as this is a hack and not intended by designers, it can result in many issues. Certain systems can have an overclocked CPU with few if any issues, while others can not overclock without major issues.
Contents
Chart
System | Normal clock | Hardware Overclock | Emulation Overclock | Overclock levels |
---|---|---|---|---|
NES | 1.79 MHz | Yes | No | ? |
SNES CPU | 3.58 MHz | Yes | No | ? |
SNES SFX1 | 10.5 MHz | Yes | Yes | - |
SNES SFX2 | 21 MHz | Yes | Yes | 40-60 Mhz, |
Mega Drive | 7.7 MHz | Yes[1] | No | 13.1-25.4 MHz[1] |
PlayStation | 33.8 MHz | Yes[2] | No | 66Mhz[2] |
Sega Saturn | 28.6 MHz* | No | No | - |
Nintendo 64 | 93.75 MHz | Yes[3] | Yes | 125-187.5 Mhz[3] |
Neo Geo | 12 MHz | Yes[4] | Yes | 14-18 MHz[4] |
*Sega Saturn has two SH-2 CPUs
Famicom (NES)
Since so many graphical tricks in famicom games are based on extremely careful timing (even things as mundane as the status bars in games like The Legend of Zelda), overclocking would likely cause many graphical issues. It is likely for this reason that there is no Famicom emulator that has overclocking options.
SNES
Main CPU
The main SNES CPU ran at 3.58 MHz and can be overclocked. However it causes issues. With those who have tested it, the following issues occur:
- "4.1 MHz: Small amounts of sprite breakup occasionally; very little slowdown.
- 5.1 MHz: Sprite breakup; no slowdown
- 6.6 MHz: Color palette errors; sprites fail to render
- 7.6 MHz: Color palette errors; sprites fail to render. Freezes after a few minutes."[5]
There are no SNES emulators that allow for an overclocking option, likely because of those issues.
SFX chip
The first version of the chip, commonly referred to as simply "Super FX", is clocked with a 21 MHz signal, but an internal clock speed divider halves it to 10.5 MHz. Later on, the design was revised to become the Super FX GSU-2; this, unlike the first Super FX chip revision, is able to reach 21 MHz.
The SFX chip however can be overclocked with fewer issues on real hardware or emulation. It does however increase the speed of the game as well.
Tests have shown that overclocking can increase the speed of the game, in addition to increasing the framerate and removing slodown.[6]
Clock speed | Time | Increase |
---|---|---|
Normal | 1'46'02 | ------- |
50hz | 1'23'78 | 27.711%[6] |
Snes9x-Next allows for SFX overclocking.
N64
Mupen64Plus - VI Refresh
GameCube/Wii
Dolphin - VBeam Speed Hack doubles GPU clock rate.
PS2
PCSX2 - VU Cycle Stealing allows for increased GPU performance at the cost of CPU cycles.
Neo Geo
Final burn alpha. Issues???
Mega Drive
Can be overclocked leading to faster/smoother gameplay. http://www.youtube.com/watch?v=SVrElANZg2M
No MegaDrive emulator currently supports overclocking.
The Genesis Plus GX dev says that implementing overclocking is "not easy to add without potentially break other things. "[7]
References
- ↑ 1.0 1.1 http://kyorune.com/modding/article.php?id=73
- ↑ 2.0 2.1 https://www.youtube.com/watch?v=HapnSOseDfw
- ↑ 3.0 3.1 http://www.gamesx.com/misctech/n64oc.htm
- ↑ 4.0 4.1 http://www.neo-geo.com/forums/showthread.php?158016-68K-s-guide-to-overclocking-your-Neo-Geo-AES
- ↑ http://web.archive.org/web/20070629163744/http://www.undergroundcm.com/index.php?option=com_content&task=view&id=15&Itemid=38
- ↑ 6.0 6.1 https://www.youtube.com/watch?v=tfNI3HpUt-4
- ↑ https://code.google.com/p/genplus-gx/issues/detail?id=223