Changes

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 framerateframe rate. 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.

| style="text-align: center;"|[[Super Nintendo emulators|SNES]] (Main CPU)

| style="text-align: center;"|NoYes

| style="text-align: center;"|[[Super Nintendo emulators|SNES]] SFX1(Super FX 1)

| style="text-align: center;"|[[Super Nintendo emulators|SNES]] SFX2(Super FX 2)

<nowiki>*</nowiki>Sega Saturn has two SH-2 CPUs

*"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."<ref name="SNES overclock">http://web.archive.org/web/20070629163744/http://www.undergroundcm.com/index.php?option=com_content&task=view&id=15&Itemid=38</ref>

There are no Only MAME has an option to change the main CPU frequency, which requires you to enable cheats. MAME SNES emulators that emulation is very demanding by default, and activating the overclock only makes it worse. It is more stable than the real hardware while overclocked and won't exhibit the same issues, but it is still very unstable especially if you adjust the frequency multiple times. It also does not allow for an overclocking optionyou to go over 200% clock speed, likely because which isn't enough to fully get rid of those issuesslowdowns in some games.  ===SFX chip===

The SFX chip however can be overclocked with fewer issues on real hardware or emulation. It does however increase with fewer issues than overclocking the speed of the game as wellCPU.  Tests However, tests have shown that overclocking can increase the speed of the game, in addition to increasing the framerate frame rate and removing slodownslowdown.<ref name="Dragon50hztest">https://www.youtube.com/watch?v=tfNI3HpUt-4</ref>

Overclocking the The main CPU can be overclocked on real hardware but will also has the effect of speeding speed up the audio as well.<ref>When you overclock the CPU, the audio speeds up as wellhttp://nfggames.com/games/pce/</ref>

Some emulators like the [[RetroArchLibretro|libretro]] port of [[Mupen64Plus]] have an overclocking option called "VI Refresh", and 1964 UltraFast (a very old fork of 1964) have an option to overclock the CPU.

Some games (see the list below) can take advantage of overclocking and improves framerateframe rate, while most others (such as Super Mario 64) have built-in framerate frame rate limiter and unaffected by overclocking.<ref>http://forum.pj64-emu.com/showpost.php?p=51810&postcount=6</ref><ref>http://www.emucr.com/2011/02/1964-ultrafast-v3.html</ref>

Disney's Donald Duck - Goin ' Quackers / Donald Duck - Quack Attack

Goldeneye GoldenEye 007

On emulators, [https://github.com/SonofUgly/PCSX-Reloaded/releases this modified build] of [[PCSX-Reloaded|PCSX-R allows ]] as well as [http://ngemu.com/threads/pcsxr-pgxp.186369/ this fork] allow for overclocking, though most games will break past 1.5x clock-speed. Recent builds of Beetle PSX ([[Libretro]] libretro fork of [[Mednafen]]'s PS1 core) also support overclocking, by way of removing timing penalties instead increasing clock speed.

On original model PS2s you can overclock by a small amount without too much problem, but the biggest issue will be sped -up audio. Slim model PS2s use the GPU's clockrate clock rate as a base for the CPU (multiplying the GPU's clock by 2), so overclocking the CPU will also overclock the GPU resulting in many visual problems.<ref name="PS2OC">http://nfggames.com/forum2/index.php?topic=2220.0</ref>

All recent builds of [[PCSX2 ]] have a speed hack that allows you to increase the EE cycle-rate without having any effect on the audio, although it does still break a few games most of them run fine and with less slowdown. The emulator also has a speed hack called VU Cycle Stealing, which allows for increased GPU performance at the cost of CPU cycles. It gives an incorrect FPS readout, though.

[[PPSSPP]] allows over/underclocking of the main CPU. Due to Sony underclocking the CPU to 222 MHz then removing the underclock in a later firmware update to allow it to run at 333 MHz<ref>https://en.wikipedia.org/wiki/PlayStation_Portable_hardware#Technical_specifications</ref> (and thus not having games closely tied to clockrateclock rate), overclocking the system (and emulating an overclocked system) results to next to no ill effects. 

[[Final burn alpha Burn Alpha]] allows for overclocking of Neo Geo games. MAMEUIFX (aka MAME32FX) also allows for overclocking.<ref>http://mame32fx.altervista.org/home.htm</ref> All Neo Geo should run at full speed when overclocked.

The original hardware can be overclocked leading to faster/smoother gameplay. <ref>http://www.youtube.com/watch?v=SVrElANZg2M</ref>

Most Genesis emulators don't allow overclocking. The [[Genesis Plus GX]] devdeveloper, for instance, says that implementing overclocking is "not easy to add without potentially break other things. "<ref>https://code.google.com/p/genplus-gx/issues/detail?id=223</ref>

Standalone Windows version of 4DO allows up to 400% of the original 3DO clock speed, making some low framerate frame rate titles such as Doctor Hauzer more playable. (The libretro version of 4DO does not seem to contain overclocking features).