First I would check the Display (HDTV) Manual PDF for how to switch between TV - PC - GAME - MOVIE Modes they provide.
Most will ... Samsung for example attach this functionality typically to only 1 of the HDMI Ports, and you must Rename the port to PC for it to switch to PC / DVI Compliant Mode.
This will typically resolve said issue in most cases.
If this doesn't work, then under the Display Tab (you say that HDMI Scaling is disabled?) there are two things you can try.
Either Enable GPU Scaling, this should blank the screen for a second but usually enable the HDMI Scaling... or alternatively create a Custom Resolution, where you can tweak the default timings (you'll want to reduce the Horizontal and Vertical Timings by ~10% based on the image) and this should resolve the issue.
Note for the second method you will have to do this for EACH Resolution you Plan to use as it Overrides the Default Timing Table the Drivers use.
Alternatively drop the Resolution to 1700x1000 ... typically when this occurs it's because you're not using a Full HD but rather just a HD Display, so while it supports 1080p ... strictly speaking it's actually downscaling it to a Native Resolution, and so what's happening is the Graphics Drivers are detecting said Native Resolution and Scaling, which the TV itself is then further Scaling. This is why you want to be using the GPU Scaling to offset the said Scaling.
Also IF your display supports it, switch to a DVI or Display Port Cable. This issue is exclusive to HDMI and Non-Native Full HD Displays.
Switching to DVI / Display Port will only allow the System to use the Native Resolution, and the TV itself will disable Scaling (which again that's what PC Mode is supposed to).