Difference between revisions of "Overclocking"

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==GameCube/Wii==
 
==GameCube/Wii==
[[Dolphin]] - VBeam Speed Hack doubles GPU clock rate.
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Recent builds of [[Dolphin]] support overclocking and underclocking the CPU. Overclocking can remove slowdown from games that have them, pushing them closer to their actual locked framerate. It causes several issues with many games, so don't expect it to be a perfect solution.
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Dolphin also has a VBeam Speed Hack that doubles GPU clock rate. The developers don't prefer it be used, and it and can currently only be enabled on a per-game basis.
  
 
==PS2==
 
==PS2==

Revision as of 06:13, 5 February 2015

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.

Chart

System Normal clock Hardware Overclock Emulation Overclock Overclock levels
NES 1.79 MHz Yes No ?
SNES Main CPU 3.58 MHz Yes No 4.1 -7.6 Mhz
SNES SFX1 10.5 MHz Yes Yes 40-60 Mhz
SNES SFX2 21 MHz Yes Yes 40-60 Mhz,
Mega Drive 7.7 MHz Yes[1] Yes 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)

Overclocking is possible on real hardware, but no emulator allows for it.

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, as well as bsnes-mercury, though in the latter the increase in CPU requirements can be noticeable.

PC-Engine (TG-16)

Overclocking the main CPU also has the effect of speeding up the audio as well.[7]

N64

Mupen64Plus - VI Refresh

GameCube/Wii

Recent builds of Dolphin support overclocking and underclocking the CPU. Overclocking can remove slowdown from games that have them, pushing them closer to their actual locked framerate. It causes several issues with many games, so don't expect it to be a perfect solution.

Dolphin also has a VBeam Speed Hack that doubles GPU clock rate. The developers don't prefer it be used, and it and can currently only be enabled on a per-game basis.

PS2

On fat older PS2's you can overclock by a small amount without too much problem, the biggest issue will be sped up audio. Slim model PS2's use the GPU's clockrate 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.[8]

PCSX2 uses the CPU clock as a base, and divides for GPU clockrate, so overclocking will result in visual problems too, as well as sped up audio. PCSX2 OC Builds

PCSX2 Also has a speed hack called VU Cycle Stealing, which allows for increased GPU performance at the cost of CPU cycles. It does give incorrect FPS readout.

PSP

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[9] (and thus not having games closely tied to clockrate), overclocking the system (and emulating an overclocked system) results to next to no ill effects.

Neo Geo

Final burn alpha allows for overclocking of Neo Geo games. MAMEUIFX (aka MAME32FX) also allows for overclocking.[10] All Neo Geo should run at full speed when overclocked.

Mega Drive

The original hardware can be overclocked leading to faster/smoother gameplay. [11]

The Genesis Plus GX dev says that implementing overclocking is "not easy to add without potentially break other things. "[12]

The Regen emulator allows overclocking in the dev build version.[13] Games with sprite flicker, like Altered Beast, and games with slowdown, like Rambo III or Mega Man: The Wily Wars, play perfectly with Regen's "Overclock M68000" setting at 732 (1.5x original speed). The game speed and audio are unaffected by overclocking.

References