HD video from laptop to HDTV - "Clone" or "Single?

[mr-scarface]

So my laptop is connected to my TV via hdmi for watching movies. It's a dual core laptop but it isn't the fastest. CPU usage hovers around 60-70% during 1080p mkv playback (using coreavc). When I connect my laptop to the TV, I usually have it set to "clone" (in the nvidia control panel). This means that the laptop's display is cloned onto the TV. So this means if i'm playing a movie, it will display it both on the laptop screen, and on the tv screen. The cpu/gpu is essentially rendering the video twice right?

Should I set the display mode to "single"? Would this help performance as now it's only rendering on the tv screen? or is this not how it works? The reason I'm asking is because last night I was watching Sin City 1080p mkv and while the cpu usage was at 60% most of the time, it suddenly spiked to 100%. This is because it overheats and throttles down 1 of the 2 cores. The movie was obviously unwatchable when the cpu is at 100%.


PS: 720p releases usually take less cpu cycles on my machine (20-40%). Never had a problem with those. But I just can't imagine how a 2 hour span of 60-70% cpu usage can cause such a big problem. I've even applied a bios update which addressed an overheating issue in the past.

[jagabo]

It's quite common for laptops to have inadequate cooling. I don't think switching from clone mode to a single display will make much difference. It's worth a try though. Few laptops have hardware decoding by the GPU so the CPU is doing all the decoding (hence the high CPU usage). The GPU is working a little harder sending the decompressed video to two devices but that's not much of a power drain.