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This section describes potential problems/question that could arise when using FCEUX.

Slow emulation / Sound crackle

FCEUX may not run well on slow CPUs.

Ensure that you're using the Old PPU, because the New PPU engine is very slow. Check Config -> PPU -> Old PPU.

Sound crackle

If you enable hardware acceleration and Vsync (Wait for VBlank), and your monitor has a framerate different from 60FPS, you may experience minor sound cracle. This is a known issue and will probably be resolved in a future release.

Emulated picture is blurred (similar to the bilinear filter)

Try choosing different options in the "DirectDraw" list in the Video config dialog.

Slow savestates when recording movies

On slower computers, savestates can be slow with long movies.  A small speedup can be done by disabling Config -> Enable -> Backup savestates.

The colors in game X do not look right!

There's no such thing as a universally right palette for NES games.

FCEUX uses the color palette of the old FCEU / FCEUXD branches. Also FCEUX comes pre-packaged with several additional color palettes. For more information see Palette config and Palette options.

I converted a .fcm file to .fm2, but the .fm2 desyncs

Depending on what version of FCEU / Game your .fcm was made, there maybe a number of sync issues. In addition, the .fm2 conversion tool has had some issues on certain operating systems including Vista and Mac. you can try using an external program for movie conversion.

Can't find FDS Bios image when I attempt to load a .fds game!

FCEUX requires the FDS Bios to be named disksys.rom. It must be located in the root directory (where fceux.exe is stored) or in the folder of the FDS Directory override (see Directory overrides).

In addition, there are some bad versions of disksys.rom. The one FDS requires is 8192 bytes in size.

How can I use Netplay / Where can I get FCEU Server?

Currently, the Windows version of FCEUX is barely compatible with the FCEU-server code. This is a known issue and will probably be resolved in a future release.

I have a Game Genie rom, how can I use it with FCEUX?

While FCEUX has a Game Genie code converter, you can also use game genie codes with an old-school Game Genie ROM.  It must be named gg.rom and must be placed in the root directory (where fceux.exe is stored). You must also check Config->Enable->Game Genie ROM in the main menu. Then the Game Genie ROM will activate every time you open a ROM, so you can enter GG codes letter-by-letter like they did in the past.

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