
NVIDIA just released a set of graphics drivers for Windows and Linux with OpenGL 4.5 support. These drivers are intended for graphics developers.
You can download R340.65 from this page.

For a GeForce GTX 750, R340.65 exposes 343 OpenGL extensions (GL=315 and WGL=28) under Windows 8 64-bit.
The complete list (submitted with GPU Caps Viewer 1.20.1) of all extensions if available in THIS ENTRY of the GPU database.
The GL_KHR_context_flush_control is not exposed by R340.65. However, R340.65 exposes GL_ARB_context_flush_control and WGL_ARB_context_flush_control.
The nice thing is that NVIDIA has added the driver version to the GL_VERSION query:
GL_VERSION = 4.5.0 NVIDIA 340.65
Yeah!

Here is the complete list of all OpenGL extensions exposed for the GTX 750. In bold, the new extensions added by R340.60:
- GL_AMD_multi_draw_indirect
- GL_AMD_seamless_cubemap_per_texture
- GL_ARB_arrays_of_arrays (OpenGL 4.3)
- GL_ARB_base_instance (OpenGL 4.2)
- GL_ARB_bindless_texture (OpenGL 4.4)
- GL_ARB_blend_func_extended (OpenGL 3.3)
- GL_ARB_buffer_storage (OpenGL 4.4)
- GL_ARB_clear_buffer_object (OpenGL 4.3)
- GL_ARB_clear_texture (OpenGL 4.4)
- GL_ARB_clip_control (OpenGL 4.5)
- GL_ARB_color_buffer_float (OpenGL 3.0)
- GL_ARB_compatibility (OpenGL 3.2)
- GL_ARB_compressed_texture_pixel_storage (OpenGL 4.2)
- GL_ARB_conservative_depth (OpenGL 4.2)
- GL_ARB_compute_shader (OpenGL 4.3)
- GL_ARB_compute_variable_group_size (OpenGL 4.3)
- GL_ARB_conditional_render_inverted (OpenGL 4.5)
- GL_ARB_context_flush_control
- GL_ARB_copy_buffer (OpenGL 3.1)
- GL_ARB_copy_image (OpenGL 4.3)
- GL_ARB_cull_distance (OpenGL 4.5)
- GL_ARB_debug_output (OpenGL 3.0)
- GL_ARB_depth_buffer_float (OpenGL 3.0)
- GL_ARB_depth_clamp (OpenGL 3.2)
- GL_ARB_depth_texture (OpenGL 1.4)
- GL_ARB_derivative_control (OpenGL 4.5)
- GL_ARB_direct_state_access (OpenGL 4.5)
- GL_ARB_draw_buffers (OpenGL 2.0)
- GL_ARB_draw_buffers_blend (OpenGL 4.0)
- GL_ARB_draw_indirect (OpenGL 4.0)
- GL_ARB_draw_elements_base_vertex (OpenGL 3.2)
- GL_ARB_draw_instanced (OpenGL 3.1)
- GL_ARB_enhanced_layouts (OpenGL 4.4)
- GL_ARB_ES2_compatibility (OpenGL 4.1)
- GL_ARB_ES3_compatibility (OpenGL 4.3)
- GL_ARB_ES3_1_compatibility (OpenGL 4.5)
- GL_ARB_explicit_attrib_location (OpenGL 3.3)
- GL_ARB_explicit_uniform_location (OpenGL 4.3)
- GL_ARB_fragment_coord_conventions (OpenGL 3.2)
- GL_ARB_fragment_layer_viewport (OpenGL 4.3)
- GL_ARB_fragment_program (OpenGL 1.3)
- GL_ARB_fragment_program_shadow (OpenGL 1.3)
- GL_ARB_fragment_shader (OpenGL 2.0)
- GL_ARB_framebuffer_no_attachments (OpenGL 4.3)
- GL_ARB_framebuffer_object (OpenGL 3.0)
- GL_ARB_framebuffer_sRGB (OpenGL 3.0)
- GL_ARB_geometry_shader4 (OpenGL 3.2)
- GL_ARB_get_program_binary (OpenGL 4.1)
- GL_ARB_get_texture_sub_image (OpenGL 4.5)
- GL_ARB_gpu_shader5 (OpenGL 4.0)
- GL_ARB_gpu_shader_fp64 (OpenGL 4.0)
- GL_ARB_half_float_pixel (OpenGL 3.0)
- GL_ARB_half_float_vertex (OpenGL 2.1)
- GL_ARB_imaging
- GL_ARB_indirect_parameters (OpenGL 4.3)
- GL_ARB_instanced_arrays (OpenGL 3.3)
- GL_ARB_internalformat_query (OpenGL 4.2)
- GL_ARB_internalformat_query2 (OpenGL 4.3)
- GL_ARB_invalidate_subdata (OpenGL 4.3)
- GL_ARB_map_buffer_alignment (OpenGL 4.2)
- GL_ARB_map_buffer_range (OpenGL 2.1)
- GL_ARB_multi_bind (OpenGL 4.4)
- GL_ARB_multi_draw_indirect (OpenGL 4.3)
- GL_ARB_multisample (OpenGL 1.3)
- GL_ARB_multitexture (OpenGL 1.3)
- GL_ARB_occlusion_query (OpenGL 1.5)
- GL_ARB_occlusion_query2 (OpenGL 3.3)
- GL_ARB_pipeline_statistics_query
- GL_ARB_pixel_buffer_object (OpenGL 2.1)
- GL_ARB_point_parameters (OpenGL 1.4)
- GL_ARB_point_sprite (OpenGL 2.0)
- GL_ARB_program_interface_query (OpenGL 4.3)
- GL_ARB_provoking_vertex (OpenGL 3.2)
- GL_ARB_robust_buffer_access_behavior (OpenGL 4.3)
- GL_ARB_robustness (OpenGL 4.1)
- GL_ARB_sample_shading (OpenGL 4.0)
- GL_ARB_sampler_objects (OpenGL 3.3)
- GL_ARB_seamless_cube_map (OpenGL 3.2)
- GL_ARB_seamless_cubemap_per_texture (OpenGL 4.3)
- GL_ARB_separate_shader_objects (OpenGL 4.1)
- GL_ARB_shader_atomic_counters (OpenGL 4.2)
- GL_ARB_shader_bit_encoding (OpenGL 3.3)
- GL_ARB_shader_draw_parameters (OpenGL 4.3)
- GL_ARB_shader_group_vote (OpenGL 4.3)
- GL_ARB_shader_image_load_store (OpenGL 4.2)
- GL_ARB_shader_image_size (OpenGL 4.3)
- GL_ARB_shader_objects (OpenGL 2.0)
- GL_ARB_shader_precision (OpenGL 4.1)
- GL_ARB_query_buffer_object (OpenGL 4.4)
- GL_ARB_shader_storage_buffer_object (OpenGL 4.3)
- GL_ARB_shader_subroutine (OpenGL 4.0)
- GL_ARB_shader_texture_image_samples (OpenGL 4.5)
- GL_ARB_shader_texture_lod (OpenGL 2.0)
- GL_ARB_shading_language_100 (OpenGL 2.0)
- GL_ARB_shading_language_420pack (OpenGL 4.2)
- GL_ARB_shading_language_include (OpenGL 3.2)
- GL_ARB_shading_language_packing (OpenGL 4.1)
- GL_ARB_shadow (OpenGL 1.4)
- GL_ARB_sparse_buffer
- GL_ARB_sparse_texture (OpenGL 4.3)
- GL_ARB_stencil_texturing (OpenGL 4.3)
- GL_ARB_sync (OpenGL 3.2)
- GL_ARB_tessellation_shader (OpenGL 4.0)
- GL_ARB_texture_barrier (OpenGL 4.5)
- GL_ARB_texture_border_clamp (OpenGL 1.3)
- GL_ARB_texture_buffer_object (OpenGL 3.1)
- GL_ARB_texture_buffer_object_rgb32 (OpenGL 4.0)
- GL_ARB_texture_buffer_range (OpenGL 4.3)
- GL_ARB_texture_compression (OpenGL 1.3)
- GL_ARB_texture_compression_bptc (OpenGL 4.2)
- GL_ARB_texture_compression_rgtc (OpenGL 3.0)
- GL_ARB_texture_cube_map (OpenGL 1.3)
- GL_ARB_texture_cube_map_array (OpenGL 4.0)
- GL_ARB_texture_env_add (OpenGL 1.3)
- GL_ARB_texture_env_combine (OpenGL 1.3)
- GL_ARB_texture_env_crossbar (OpenGL 1.4)
- GL_ARB_texture_env_dot3 (OpenGL 1.3)
- GL_ARB_texture_float (OpenGL 3.0)
- GL_ARB_texture_gather (OpenGL 4.0)
- GL_ARB_texture_mirror_clamp_to_edge (OpenGL 4.4)
- GL_ARB_texture_mirrored_repeat (OpenGL 1.4)
- GL_ARB_texture_multisample (OpenGL 3.2)
- GL_ARB_texture_non_power_of_two
- GL_ARB_texture_query_levels (OpenGL 4.3)
- GL_ARB_texture_query_lod (OpenGL 4.0)
- GL_ARB_texture_rectangle (OpenGL 3.1)
- GL_ARB_texture_rg (OpenGL 3.0)
- GL_ARB_texture_rgb10_a2ui (OpenGL 3.3)
- GL_ARB_texture_stencil8 (OpenGL 4.4)
- GL_ARB_texture_storage (OpenGL 4.2)
- GL_ARB_texture_storage_multisample (OpenGL 4.3)
- GL_ARB_texture_swizzle (OpenGL 3.3)
- GL_ARB_texture_view (OpenGL 4.3)
- GL_ARB_timer_query (OpenGL 3.3)
- GL_ARB_transform_feedback2 (OpenGL 4.0)
- GL_ARB_transform_feedback3 (OpenGL 4.0)
- GL_ARB_transform_feedback_instanced (OpenGL 4.2)
- GL_ARB_transform_feedback_overflow_query
- GL_ARB_transpose_matrix (OpenGL 1.3)
- GL_ARB_uniform_buffer_object (OpenGL 3.1)
- GL_ARB_vertex_array_bgra (OpenGL 3.2)
- GL_ARB_vertex_array_object (OpenGL 2.1)
- GL_ARB_vertex_attrib_64bit (OpenGL 4.1)
- GL_ARB_vertex_attrib_binding (OpenGL 4.3)
- GL_ARB_vertex_buffer_object (OpenGL 1.5)
- GL_ARB_vertex_program (Requires OpenGL 1.3)
- GL_ARB_vertex_shader (OpenGL 2.0)
- GL_ARB_vertex_type_10f_11f_11f_rev (OpenGL 4.4)
- GL_ARB_vertex_type_2_10_10_10_rev (OpenGL 3.3)
- GL_ARB_viewport_array (OpenGL 4.1)
- GL_ARB_window_pos (OpenGL 1.4)
- GL_ATI_draw_buffers (Requires OpenGL 1.3)
- GL_ATI_texture_float (Requires OpenGL 1.3)
- GL_ATI_texture_mirror_once (Requires OpenGL 1.2.1)
- GL_S3_s3tc
- GL_EXT_texture_env_add
- GL_EXT_abgr
- GL_EXT_bgra (OpenGL 1.2)
- GL_EXT_bindable_uniform (OpenGL 2.0)
- GL_EXT_blend_color (OpenGL 1.4 OpenGL 1.4)
- GL_EXT_blend_equation_separate
- GL_EXT_blend_func_separate (Requires OpenGL 1.2 / Core Feature of OpenGL 1.4)
- GL_EXT_blend_minmax (Requires OpenGL 1.2)
- GL_EXT_blend_subtract (Requires OpenGL 1.2)
- GL_EXT_compiled_vertex_array (Requires OpenGL 1.1)
- GL_EXT_Cg_shader
- GL_EXT_depth_bounds_test
- GL_EXT_direct_state_access
- GL_EXT_draw_buffers2 (OpenGL 3.0)
- GL_EXT_draw_instanced (Requires OpenGL 2.0)
- GL_EXT_draw_range_elements (Requires OpenGL 1.2 / Core Feature of OpenGL 1.4)
- GL_EXT_fog_coord (Requires OpenGL 1.2 / Core Feature of OpenGL 1.4)
- GL_EXT_framebuffer_blit (OpenGL 3.0)
- GL_EXT_framebuffer_multisample (OpenGL 3.0)
- GL_EXTX_framebuffer_mixed_formats
- GL_EXT_framebuffer_multisample_blit_scaled
- GL_EXT_framebuffer_object (Requires OpenGL 3.0)
- GL_EXT_framebuffer_sRGB (OpenGL 3.0)
- GL_EXT_geometry_shader4 (Requires OpenGL 2.0)
- GL_EXT_gpu_program_parameters (Requires OpenGL 2.0)
- GL_EXT_gpu_shader4 (OpenGL 3.0)
- GL_EXT_multi_draw_arrays (OpenGL 1.2 / Core Feature of OpenGL 1.4)
- GL_EXT_packed_depth_stencil (OpenGL 3.0)
- GL_EXT_packed_float (OpenGL 3.0)
- GL_EXT_packed_pixels (Requires OpenGL 1.2)
- GL_EXT_pixel_buffer_object
- GL_EXT_point_parameters
- GL_EXT_provoking_vertex
- GL_EXT_rescale_normal (Requires OpenGL 1.2)
- GL_EXT_secondary_color (Requires OpenGL 1.2 / Core Feature of OpenGL 1.4)
- GL_EXT_separate_shader_objects
- GL_EXT_separate_specular_color (Requires OpenGL 1.2)
- GL_EXT_shader_image_load_formatted
- GL_EXT_shader_image_load_store
- GL_EXT_shader_integer_mix
- GL_EXT_shadow_funcs (Requires OpenGL 1.3 / Core Feature of OpenGL 1.5)
- GL_EXT_stencil_two_side
- GL_EXT_stencil_wrap (Requires OpenGL 1.4)
- GL_EXT_texture3D (Requires OpenGL 1.2)
- GL_EXT_texture_array (OpenGL 3.0)
- GL_EXT_texture_buffer_object (Requires OpenGL 2.0)
- GL_EXT_texture_compression_dxt1
- GL_EXT_texture_compression_latc
- GL_EXT_texture_compression_rgtc (OpenGL 3.0)
- GL_EXT_texture_compression_s3tc (Requires OpenGL 1.2.1)
- GL_EXT_texture_cube_map (See GL_ARB_texture_cube_map)
- GL_EXT_texture_edge_clamp
- GL_EXT_texture_env_combine
- GL_EXT_texture_env_dot3
- GL_EXT_texture_filter_anisotropic (Requires OpenGL 1.2)
- GL_EXT_texture_integer (OpenGL 3.0)
- GL_EXT_texture_lod
- GL_EXT_texture_lod_bias (Requires OpenGL 1.2 / Core Feature of OpenGL 1.4)
- GL_EXT_texture_mirror_clamp (Requires OpenGL 1.4)
- GL_EXT_texture_object (Requires OpenGL 1.1)
- GL_EXT_texture_shared_exponent (OpenGL 3.0)
- GL_EXT_texture_sRGB
- GL_EXT_texture_sRGB_decode
- GL_EXT_texture_storage
- GL_EXT_texture_swizzle (OpenGL 2.1)
- GL_EXT_timer_query (Requires OpenGL 1.5)
- GL_EXT_transform_feedback2
- GL_EXT_vertex_array (Requires OpenGL 1.1)
- GL_EXT_vertex_array_bgra
- GL_EXT_vertex_attrib_64bit
- GL_EXT_import_sync_object
- GL_IBM_rasterpos_clip
- GL_IBM_texture_mirrored_repeat
- GL_KHR_debug (OpenGL 4.3)
- GL_KHR_robust_buffer_access_behavior
- GL_KHR_robustness (OpenGL 4.5)
- GL_KTX_buffer_region
- GL_NV_bindless_multi_draw_indirect
- GL_NV_bindless_multi_draw_indirect_count
- GL_NV_bindless_texture (OpenGL 4.0)
- GL_NV_blend_equation_advanced
- GL_NV_blend_equation_advanced_coherent
- GL_NV_blend_square (Requires OpenGL 1.2.1 / Core Feature of OpenGL 1.4)
- GL_NV_compute_program5
- GL_NV_conditional_render (OpenGL 3.0)
- GL_NV_copy_depth_to_color
- GL_NV_copy_image
- GL_NV_depth_buffer_float (OpenGL 3.0)
- GL_NV_depth_clamp
- GL_NV_draw_texture
- GL_NV_ES1_1_compatibility
- GL_NV_ES3_1_compatibility
- GL_NV_explicit_multisample
- GL_NV_fence
- GL_NV_float_buffer
- GL_NV_fog_distance
- GL_NV_fragment_program
- GL_NV_fragment_program_option
- GL_NV_fragment_program2
- GL_NV_framebuffer_multisample_coverage
- GL_NV_geometry_shader4
- GL_NV_gpu_program4
- GL_NV_gpu_program4_1
- GL_NV_gpu_program5
- GL_NV_gpu_program5_mem_extended
- GL_NV_gpu_program_fp64
- GL_NV_gpu_shader5
- GL_NV_half_float (OpenGL 3.0)
- GL_NV_light_max_exponent
- GL_NV_multisample_coverage
- GL_NV_multisample_filter_hint
- GL_NV_occlusion_query (Requires OpenGL 1.3)
- GL_NV_packed_depth_stencil
- GL_NV_parameter_buffer_object
- GL_NV_parameter_buffer_object2
- GL_NV_path_rendering
- GL_NV_pixel_data_range
- GL_NV_point_sprite
- GL_NV_primitive_restart (OpenGL 3.1)
- GL_NV_register_combiners
- GL_NV_register_combiners2
- GL_NV_shader_atomic_counters
- GL_NV_shader_atomic_float
- GL_NV_shader_atomic_int64
- GL_NV_shader_buffer_load
- GL_NV_shader_storage_buffer_object
- GL_NV_texgen_reflection (Requires OpenGL 1.3)
- GL_NV_texture_barrier
- GL_NV_texture_compression_vtc
- GL_NV_texture_env_combine4
- GL_NV_texture_expand_normal
- GL_NV_texture_multisample
- GL_NV_texture_rectangle
- GL_NV_texture_shader
- GL_NV_texture_shader2
- GL_NV_texture_shader3
- GL_NV_transform_feedback
- GL_NV_transform_feedback2
- GL_NV_vertex_array_range
- GL_NV_vertex_array_range2
- GL_NV_vertex_attrib_integer_64bit
- GL_NV_vertex_buffer_unified_memory
- 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_NVX_gpu_memory_info
- GL_NVX_nvenc_interop
- GL_NV_shader_thread_group
- GL_NV_shader_thread_shuffle
- GL_KHR_blend_equation_advanced
- GL_KHR_blend_equation_advanced_coherent
- GL_SGIS_generate_mipmap (Requires OpenGL 1.4)
- GL_SGIS_texture_lod (Requires OpenGL 1.2)
- GL_SGIX_depth_texture
- GL_SGIX_shadow
- GL_SUN_slice_accum
- GL_WIN_swap_hint
- WGL_EXT_swap_control (Requires OpenGL 1.2)
- WGL_ARB_buffer_region
- WGL_ARB_create_context (OpenGL 3.0)
- WGL_ARB_create_context_profile
- WGL_ARB_create_context_robustness (OpenGL 4.1)
- WGL_ARB_context_flush_control
- WGL_ARB_extensions_string
- WGL_ARB_make_current_read
- WGL_ARB_multisample
- WGL_ARB_pbuffer
- WGL_ARB_pixel_format
- WGL_ARB_pixel_format_float
- WGL_ARB_render_texture (Requires OpenGL 1.1)
- WGL_ATI_pixel_format_float (Requires OpenGL 1.3)
- WGL_EXT_create_context_es_profile
- WGL_EXT_create_context_es2_profile
- WGL_EXT_extensions_string
- WGL_EXT_framebuffer_sRGB (OpenGL 2.0)
- WGL_EXT_pixel_format_packed_float (OpenGL 2.0)
- WGL_EXT_swap_control_tear
- WGL_NVX_DX_interop
- WGL_NV_DX_interop
- WGL_NV_DX_interop2
- WGL_NV_delay_before_swap
- WGL_NV_float_buffer
- WGL_NV_multisample_coverage
- WGL_NV_render_depth_texture
- WGL_NV_render_texture_rectangle
http://www.slideshare.net/Mark_Kilgard/opengl-45-update-for-nvidia-gpus
https://developer.nvidia.com/cuda-downloads
http://devblogs.nvidia.com/parallelforall/10-ways-cuda-6-5-improves-performance-productivity/
CUDA 6.5 released.
http://delphigl.de/glcapsviewer/gl_generatereport.php?reportID=590
GL_KHR_context_flush_control is exposed by 340.76 beta OpenGL 4.5 driver.
https://developer.nvidia.com/opengl-driver
“Windows driver version 340.82 and Linux drivers version 340.23.03 provide beta support for OpenGL 4.5 and GLSL 4.50 on capable hardware.”
Does NVIDIA have any timeline on releasing an OpenGL 4.5 compatible driver for the new Maxwell cards?