UserAgent: Mozilla/5.0 (X11; CrOS x86_64 9592.96.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.114 Safari/537.36
Platform: 9592.96.0 (Official Build) stable-channel guado

Example URL:
-

Steps to reproduce the problem:
1. I attached a 4K touchscreen (Prowise) to the HDMI port on the Chromebox
2. I attached a 4K monitor to the DP port (ACER CB241HQKbmjdpr) on the Chromebox
3. Playback in 4K doesn't work well. It keeps on loading.
4. additionaly: touch stops working on the touchscreen when attaching the 2nd monitor to the DP port

What is the expected behavior?
That video can be played without any hickups.

What went wrong?
I believe it's a restriction of the GPU inside a Chromebox. We have the newest Chromeboxes with the i3 5010 processor so that shouldn't be a problem. There are not any aother quicker models available right now. 

Did this work before? N/A 

Is it a problem with Flash or HTML5? HTML5

Does this work in other browsers? N/A

Chrome version: 60.0.3112.114  Channel: stable
OS Version: 9592.96.0
Flash Version: Shockwave Flash 27.0 r0

Contents of chrome://gpu: 
Graphics Feature Status
Canvas: Hardware accelerated
CheckerImaging: Disabled
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Hardware accelerated
Panel Fitting: Unavailable
Rasterization: Software only. Hardware acceleration disabled
Video Decode: Hardware accelerated
Video Encode: Hardware accelerated
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
clear_uniforms_before_first_program_use
count_all_in_varyings_packing
decode_encode_srgb_for_generatemipmap
disable_discard_framebuffer
msaa_is_slow
scalarize_vec_and_mat_constructor_args
rely_on_implicit_sync_for_swap_buffers
Problems Detected
Chrome OS panel fitting is only supported for Intel IVB and SNB Graphics Controllers
Disabled Features: panel_fitting
Framebuffer discarding causes jumpy scrolling on Mali drivers: 301988
Applied Workarounds: disable_discard_framebuffer
Clear uniforms before first program use on all platforms: 124764, 349137
Applied Workarounds: clear_uniforms_before_first_program_use
Mesa drivers in ChromeOS handle varyings without static use incorrectly: 333885
Applied Workarounds: count_all_in_varyings_packing
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
On Intel GPUs MSAA performance is not acceptable for GPU rasterization: 527565
Applied Workarounds: msaa_is_slow
Disable KHR_blend_equation_advanced until cc shaders are updated: 661715
Decode and Encode before generateMipmap for srgb format textures on Chromeos Intel: 634519
Applied Workarounds: decode_encode_srgb_for_generatemipmap
Avoid waiting on a egl fence before pageflipping and rely on implicit sync.: 721463
Applied Workarounds: rely_on_implicit_sync_for_swap_buffers
Accelerated rasterization has been disabled, either via blacklist, about:flags or the command line.
Disabled Features: rasterization
Checker-imaging has been disabled via finch trial or the command line.
Disabled Features: checker_imaging
Version Information
Data exported	6-10-2017 11:59:30
Chrome version	Chrome/60.0.3112.114
Operating system	Linux 3.14.0
Software rendering list version	13.9
Driver bug list version	10.94
ANGLE commit id	3e6a61fecba9
2D graphics backend	Skia/60 0
Command Line	/opt/google/chrome/chrome --ppapi-flash-path=/opt/google/chrome/pepper/libpepflashplayer.so --ppapi-flash-version=27.0.0.130 --ui-prioritize-in-gpu-process --use-gl=egl --enable-native-gpu-memory-buffers --gpu-sandbox-failures-fatal=yes --enable-logging --log-level=1 --use-cras --enable-wayland-server --user-data-dir=/home/chronos --max-unused-resource-memory-usage-percentage=5 --login-profile=user --aura-legacy-power-button --default-wallpaper-large=/usr/share/chromeos-assets/wallpaper/default_large.jpg --default-wallpaper-small=/usr/share/chromeos-assets/wallpaper/default_small.jpg --child-wallpaper-large=/usr/share/chromeos-assets/wallpaper/child_large.jpg --child-wallpaper-small=/usr/share/chromeos-assets/wallpaper/child_small.jpg --guest-wallpaper-large=/usr/share/chromeos-assets/wallpaper/guest_large.jpg --guest-wallpaper-small=/usr/share/chromeos-assets/wallpaper/guest_small.jpg --enable-prefixed-encrypted-media --enable-consumer-kiosk --enterprise-enrollment-initial-modulus=15 --enterprise-enrollment-modulus-limit=19 --login-manager --vmodule=*chromeos/login/*=1,auto_enrollment_controller=1,*plugin*=2,*zygote*=1,*/ui/ozone/*=1,*/ui/display/manager/chromeos/*=1,power_button_observer=2,webui_login_view=2,lock_state_controller=2,webui_screen_locker=2,screen_locker=2
Driver Information
Initialization time	22
In-process GPU	false
Passthrough Command Decoder	false
Supports overlays	false
Sandboxed	true
GPU0	VENDOR = 0x8086, DEVICE= 0x1616
Optimus	false
Optimus	false
AMD switchable	false
Driver vendor	Mesa
Driver version	17.1.0
Driver date	
Pixel shader version	3.10
Vertex shader version	3.10
Max. MSAA samples	8
Machine model name	
Machine model version	
GL_VENDOR	Intel Open Source Technology Center
GL_RENDERER	Mesa DRI Intel(R) HD Graphics 5500 (Broadwell GT2)
GL_VERSION	OpenGL ES 3.1 Mesa 17.1.0-devel (git-9baf1ff8fc)
GL_EXTENSIONS	GL_EXT_blend_minmax GL_EXT_multi_draw_arrays GL_EXT_texture_filter_anisotropic GL_EXT_texture_compression_dxt1 GL_EXT_texture_format_BGRA8888 GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth24 GL_OES_element_index_uint GL_OES_fbo_render_mipmap GL_OES_mapbuffer GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_stencil8 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_half_float GL_EXT_texture_sRGB_decode GL_OES_EGL_image GL_OES_depth_texture GL_OES_packed_depth_stencil GL_EXT_texture_type_2_10_10_10_REV GL_OES_get_program_binary GL_APPLE_texture_max_level GL_EXT_discard_framebuffer GL_EXT_read_format_bgra GL_NV_fbo_color_attachments GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_vertex_array_object GL_OES_viewport_array GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_EXT_robustness GL_EXT_texture_rg GL_EXT_unpack_subimage GL_NV_draw_buffers GL_NV_read_buffer GL_NV_read_depth GL_NV_read_depth_stencil GL_NV_read_stencil GL_EXT_draw_buffers GL_EXT_map_buffer_range GL_KHR_debug GL_KHR_robustness GL_OES_depth_texture_cube_map GL_OES_surfaceless_context GL_EXT_color_buffer_float GL_EXT_separate_shader_objects GL_EXT_shader_integer_mix GL_EXT_tessellation_point_size GL_EXT_tessellation_shader GL_EXT_copy_image GL_EXT_draw_buffers_indexed GL_EXT_draw_elements_base_vertex GL_EXT_gpu_shader5 GL_EXT_polygon_offset_clamp GL_EXT_primitive_bounding_box GL_EXT_shader_io_blocks GL_EXT_texture_border_clamp GL_EXT_texture_buffer GL_EXT_texture_cube_map_array GL_KHR_context_flush_control GL_KHR_robust_buffer_access_behavior GL_NV_image_formats GL_OES_copy_image GL_OES_draw_buffers_indexed GL_OES_draw_elements_base_vertex GL_OES_gpu_shader5 GL_OES_primitive_bounding_box GL_OES_sample_shading GL_OES_sample_variables GL_OES_shader_io_blocks GL_OES_shader_multisample_interpolation GL_OES_tessellation_point_size GL_OES_tessellation_shader GL_OES_texture_border_clamp GL_OES_texture_buffer GL_OES_texture_cube_map_array GL_OES_texture_stencil8 GL_OES_texture_storage_multisample_2d_array GL_EXT_blend_func_extended GL_EXT_buffer_storage GL_EXT_geometry_point_size GL_EXT_geometry_shader GL_EXT_shader_samples_identical GL_OES_geometry_point_size GL_OES_geometry_shader GL_OES_shader_image_atomic GL_EXT_clip_cull_distance GL_MESA_shader_integer_functions
Disabled Extensions	GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent
Window system binding vendor	Mesa Project
Window system binding version	1.4 (DRI2)
Window system binding extensions	EGL_EXT_create_context_robustness EGL_EXT_image_dma_buf_import EGL_KHR_config_attribs EGL_KHR_create_context EGL_KHR_fence_sync EGL_KHR_get_all_proc_addresses EGL_KHR_gl_renderbuffer_image EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_3D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_image_base EGL_KHR_no_config_context EGL_KHR_reusable_sync EGL_KHR_surfaceless_context EGL_KHR_wait_sync EGL_MESA_configless_context EGL_MESA_drm_image EGL_MESA_image_dma_buf_export
Direct rendering	Yes
Reset notification strategy	0x8252
GPU process crash count	0
Compositor Information
Tile Update Mode	One-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
RG_88	GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
BGR_565	GPU_READ
RGBA_4444	Software only
RGBX_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
RGBA_8888	GPU_READ, SCANOUT_CPU_READ_WRITE
BGRX_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
BGRA_8888	GPU_READ, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
RGBA_F16	Software only
YVU_420	GPU_READ
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Log Messages
[8603:8611:1006/091010.879392:VERBOSE1:drm_device_manager.cc(54)] : Could not initialize DRM device for /sys/devices/platform/vgem/drm/card1
[8603:8611:1006/091011.924893:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=20 connector=33 origin=0,0 size=1920x1200
[8603:8611:1006/091813.315360:WARNING:screen_manager.cc(114)] : Display controller (crtc=20) already present.
[8603:8611:1006/091813.315727:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=20 connector=33 origin=0,0 size=0x0
[8603:8611:1006/094655.530860:WARNING:screen_manager.cc(114)] : Display controller (crtc=20) already present.
[8603:8611:1006/094655.534459:VERBOSE1:drm_display.cc(102)] : DRM configuring: device=/sys/devices/pci0000:00/0000:00:02.0/drm/card0 crtc=20 connector=33 origin=0,0 size=1920x1200

Please make this a priority. 4K is already here. It's becoming the standard now. Please act upon this and bring more faster (GPU/CPU) chromeboxes to the markets. So we can really leave Windows behind us. Thank you!