Difference between revisions of "Overclocking"

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[http://aamirm.hacking-cult.org/www/regen.html Regen] allows overclocking in the dev build version.<ref>http://segaretro.org/Regen</ref> 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.
 
[http://aamirm.hacking-cult.org/www/regen.html Regen] allows overclocking in the dev build version.<ref>http://segaretro.org/Regen</ref> 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.
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==3DO==
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Standalone Windows version of 4DO allows up to 400% of the original 3DO clock speed, making some low framerate titles such as Doctor Hauzer more playable. (libretro version of 4DO does not seem to contain overclocking features)
  
 
==References==
 
==References==

Revision as of 01:37, 14 October 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,
Sega Genesis 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

NES

Overclocking is possible on real hardware, but doing so also speeds up the audio. No NES emulator allows overclocking.

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]

Mednafen allows overclocking the CPU up to 100x, without affecting audio pitch, in its non-default pce_fast core via the pce_fast.ocmultiplier setting.

N64

Some emulators like 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 framerate, while most others (such as Super Mario 64) have built-in framerate limiter and unaffected by overclocking.

List of games that can take advantage of overclocking

A Bug's Life
Aidyn Chronicles - The First Mage
Armorines - Project S.W.A.R.M.
Big Mountain 2000
Conker's Bad Fur Day
Destruction Derby 64
Disney's Donald Duck - Goin Quackers / Donald Duck - Quack Attack
Duck Dodgers Starring Daffy Duck / Looney Toons - Duck Dodgers
Earthworm Jim 3D
Extreme-G
Extreme-G XG2
F1 Racing Championship
F-1 Pole Position 64
Gex 3 - Deep Cover Gecko
Goldeneye 007
Hot Wheels Turbo Racing
Human Grand Prix - New Generation
Jet Force Gemini / Star Twins
Jeremy McGrath Supercross 2000
Kobe Bryant's NBA Courtside
Madden Football 64
Madden NFL 99-2002
Milo's Astro Lanes
Monaco Grand Prix - Racing Simulation 2
Monster Truck Madness 64
NASCAR 99/2000
NBA In the Zone 98 / NBA Pro 98
Off Road Challenge
Perfect Dark
Quake II
Racing Simulation 2
Rakuga Kids
Rayman 2 - The Great Escape
Roadsters Trophy
South Park Rally
StarCraft 64
Starshot - Space Circus Fever
Super Robot Spirits
Taz Express
Tom Clancy's Rainbow Six
Tonic Trouble
Toy Story 2
Transformers - Beast Wars Transmetal
Turok 2 - Seeds of Evil / Violence Killer - Turok New Generation
V-Rally Edition 99
WCW vs. nWo - World Tour
World Cup 98

Source

GameCube/Wii

Dolphin supports overclocking and underclocking the CPU. Overclocking can remove slowdown from games that have them, pushing them closer to their actual target frame rate. It causes several issues with many games, so don't expect it to be a perfect solution.

Dolphin used to have a VBeam Speed Hack that doubled GPU clock rate. This has since been removed, as the developers found that it didn't really help in any cases.

PS2

On original model PS2s you can overclock by a small amount without too much problem, the biggest issue will be sped up audio. Slim model PS2s 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. 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.

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.

Sega Genesis

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

Most Genesis emulators don't allow overclocking. The Genesis Plus GX dev, for instance, says that implementing overclocking is "not easy to add without potentially break other things. "[12]

Regen 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.

3DO

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

References