http://upload.wikimedia.org/wikipedia/commons/7/76/Kwin-cube.jpg

I already have my nvidia driver instaled.

default is ctrl+F11 to enable, the screen will shift back into the screen a bit then use the mouse to rotate the mouse (left click & hold & drag) and ctrl+F11, to disable

it's set in system settings -> desktop effects -> all effects -> desktop cube -> click wrench -> activation

Nothing happens...some clue?

Play around with the settings in the advanced tab and you may get it to work.

EDIT:
Hang on, you'd better start giving us info as to what you've tried so far. You got any effects enabled?

"You got any effects enabled?"

Hm...wich kind of efect can i use as example? Im using opengl in the options "opengl/xrender"

try using explosion or magic lamp

which Nvidia driver?

here some infos:

1) check the box explosion does not make effect

2) Change to xrender gimme info i lost lot of effects....change back to opengl gimme black screen, then i reboot and change back to opengl.

3) ~./kde/share/config/kwinrc have openglisunsafe=false

4) Instead ctrl f11 my shortcut is alt shift f12, i shall had change it by mistake...press ctrl f11 does not effect, press alt shift f12 change the color of my below tool bar, but nothing more (explosion stills no working)

5) NVIDIA 7300 GT lastest driver version 295.33 64 bits

6) # glxgears -info
GL_RENDERER = GeForce 7300 GT/PCIe/SSE2
GL_VERSION = 2.1.2 NVIDIA 295.33
GL_VENDOR = NVIDIA Corporation
GL_EXTENSIONS = GL_ARB_color_buffer_float GL_ARB_compressed_texture_pixel_storage GL_ARB_conservative_depth GL_ARB_copy_buffer GL_ARB_depth_clamp GL_ARB_depth_texture GL_ARB_draw_buffers GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location GL_ARB_fragment_program GL_ARB_fragment_program_shadow GL_ARB_fragment_shader GL_ARB_framebuffer_object GL_ARB_get_program_binary GL_ARB_half_float_pixel GL_ARB_half_float_vertex GL_ARB_imaging GL_ARB_internalformat_query GL_ARB_map_buffer_alignment GL_ARB_map_buffer_range GL_ARB_multisample GL_ARB_multitexture GL_ARB_occlusion_query GL_ARB_occlusion_query2 GL_ARB_pixel_buffer_object GL_ARB_point_parameters GL_ARB_point_sprite GL_ARB_provoking_vertex GL_ARB_robustness GL_ARB_sampler_objects GL_ARB_separate_shader_objects GL_ARB_shader_objects GL_ARB_shading_language_100 GL_ARB_shading_language_420pack GL_ARB_shading_language_include GL_ARB_shadow GL_ARB_sync GL_ARB_texture_border_clamp GL_ARB_texture_compression GL_ARB_texture_cube_map GL_ARB_texture_env_add GL_ARB_texture_env_combine GL_ARB_texture_env_crossbar GL_ARB_texture_env_dot3 GL_ARB_texture_float GL_ARB_texture_mirrored_repeat GL_ARB_texture_non_power_of_two GL_ARB_texture_rectangle GL_ARB_texture_rg GL_ARB_texture_storage GL_ARB_texture_swizzle GL_ARB_timer_query GL_ARB_transpose_matrix GL_ARB_vertex_array_bgra GL_ARB_vertex_array_object GL_ARB_vertex_buffer_object GL_ARB_vertex_program GL_ARB_vertex_shader GL_ARB_window_pos GL_ATI_draw_buffers GL_ATI_texture_float GL_ATI_texture_mirror_once GL_S3_s3tc GL_EXT_texture_env_add GL_EXT_abgr GL_EXT_bgra GL_EXT_blend_color GL_EXT_blend_equation_separate GL_EXT_blend_func_separate GL_EXT_blend_minmax GL_EXT_blend_subtract GL_EXT_compiled_vertex_array GL_EXT_Cg_shader GL_EXT_depth_bounds_test GL_EXT_direct_state_access GL_EXT_draw_range_elements GL_EXT_fog_coord GL_EXT_framebuffer_blit GL_EXT_framebuffer_multisample GL_EXT_framebuffer_object GL_EXT_gpu_program_parameters GL_EXT_multi_draw_arrays GL_EXT_packed_depth_stencil GL_EXT_packed_pixels GL_EXT_pixel_buffer_object GL_EXT_point_parameters GL_EXT_provoking_vertex GL_EXT_rescale_normal GL_EXT_secondary_color GL_EXT_separate_shader_objects GL_EXT_separate_specular_color GL_EXT_shadow_funcs GL_EXT_stencil_two_side GL_EXT_stencil_wrap GL_EXT_texture3D GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_s3tc GL_EXT_texture_cube_map GL_EXT_texture_edge_clamp GL_EXT_texture_env_combine GL_EXT_texture_env_dot3 GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_lod GL_EXT_texture_lod_bias GL_EXT_texture_mirror_clamp GL_EXT_texture_object GL_EXT_texture_sRGB GL_EXT_texture_sRGB_decode GL_EXT_texture_storage GL_EXT_texture_swizzle GL_EXT_timer_query GL_EXT_vertex_array GL_EXT_vertex_array_bgra GL_EXT_x11_sync_object GL_EXT_import_sync_object GL_IBM_rasterpos_clip GL_IBM_texture_mirrored_repeat GL_KTX_buffer_region GL_NV_alpha_test GL_NV_blend_minmax GL_NV_blend_square GL_NV_complex_primitives GL_NV_copy_depth_to_color GL_NV_depth_clamp GL_NV_fbo_color_attachments GL_NV_fence GL_NV_float_buffer GL_NV_fog_distance GL_NV_fragdepth GL_NV_fragment_program GL_NV_fragment_program_option GL_NV_fragment_program2 GL_NV_framebuffer_multisample_coverage GL_NV_half_float GL_NV_light_max_exponent GL_NV_multisample_filter_hint GL_NV_occlusion_query GL_NV_packed_depth_stencil GL_NV_pixel_data_range GL_NV_point_sprite GL_NV_primitive_restart GL_NV_register_combiners GL_NV_register_combiners2 GL_NV_texgen_reflection GL_NV_texture_barrier GL_NV_texture_compression_vtc GL_NV_texture_env_combine4 GL_NV_texture_expand_normal GL_NV_texture_lod_clamp GL_NV_texture_rectangle GL_NV_texture_shader GL_NV_texture_shader2 GL_NV_texture_shader3 GL_NV_vertex_array_range GL_NV_vertex_array_range2 GL_NV_vertex_program GL_NV_vertex_program1_1 GL_NV_vertex_program2 GL_NV_vertex_program2_option GL_NV_vertex_program3 GL_NVX_conditional_render GL_OES_depth24 GL_OES_depth32 GL_OES_depth_texture GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_texture_3D GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_vertex_array_object GL_OES_vertex_half_float GL_SGIS_generate_mipmap GL_SGIS_texture_lod GL_SGIX_depth_texture GL_SGIX_shadow GL_SUN_slice_accum
8508 frames in 5.0 seconds = 1701.529 FPS
10836 frames in 5.0 seconds = 2167.174 FPS
10073 frames in 5.0 seconds = 2014.384 FPS
7383 frames in 5.0 seconds = 1476.515 FPS
10663 frames in 5.0 seconds = 2132.501 FPS
8629 frames in 5.0 seconds = 1725.680 FPS
5677 frames in 5.0 seconds = 1135.336 FPS
5816 frames in 5.0 seconds = 1161.837 FPS
11082 frames in 5.0 seconds = 2210.729 FPS
11000 frames in 5.0 seconds = 2199.857 FPS
8292 frames in 5.0 seconds = 1658.312 FPS
10698 frames in 5.0 seconds = 2139.575 FPS
7868 frames in 5.0 seconds = 1573.590 FPS

try logging in as new user and see if the effects work

alternatively renaming ~./kde/share/config/kwinrc and restarting KDE should be equivalent

renaming kwinrc to kwinrc works!

Xplode and cube works...now i have another doubt...how i made appear all the cube in screen, as the picture i post in the start of this issue?

The way is my desktop, have two desktops on the toolbar, and when i click in one of them, creates an quick "as sheet change" effect and change the desktop to another...but does not have a cube in screen.

you need 4 desktops for a cube, more or less than 4 and the cube is what ever a number-of-desktops sided polygon is

Its strange, i already enable 4 desktops and stills just changing like a book's sheet...have another idea what it could be?

enable "desktop cube animation", the effect just below desktop cube

Ok i discovered the error...

I clicked in the wrench on that option in "all effects" and see the shortcut crtl+f11 was disable...i was making a mistake with shift alt f12, thats have another function!

Enable ctrl+f11 shotcut made the cube appears!

thanks for your patient and help!

Regards.