Quick test: Overclocked DVI is not for Nvidia Pascal

Those who are used to overclocking the monitor over DVI Dual Link should wait with Nvidia’s Pascal generation, Geforce GTX 1070 and GTX 1080. The reason is that Windows does not want to display graphics the next time the computer starts when overclocking is active, something caught by users on Reddit.

After its own tests, SweClockers can confirm that this is true, but also that the problem mainly affects Windows 10 users. If you get tough with Windows 8.1, it does not necessarily happen, but the overclocking and the higher frequency often remain under certain conditions.

Screen overclocking is about syncing screens and graphics cards at higher frequencies than is officially possible. This works because there is space left in the signal bandwidth. This is explained in detail in this article on the pixel clock.

The DVI DL limit is per specification 165 MHz per link, or a total of 330 MHz pixel clock. This is enough to run 1,920 × 1,080 pixels at 144 Hz or 2,560 × 1,440 pixels at 80 Hz. But there is no obstacle for manufacturers to add circuits that can sync with higher pixel clock and therefore reach higher frame rate. In the first place, this is something that affects those who drive so-called “Korea screens” which can be overclocked via DVI-DL.

No image after the home screen

To test, we use the faithful servant, the “Male Look” screen Acer XG270HUomidpx which runs 2,560 × 1,440 pixels in 144 Hz. It has previously impressed with the fact that it handles overclocking via DVI-DL all the way to 588 MHz pixel clock, far above the DVI specification. Which is enough to run 146 Hz frame rate in 2,560 × 1,440 pixels.

Together with the reference card of Geforce GTX 1080, we get the screen to sync to 146 Hz in 2,560 × 1,440 pixels on both computers. After startup, either hot or cold, however, the computer with Windows 10 will refuse to display the image. We reach the Windows logo and the charging circle, but instead of a desk, the screen turns black and we receive an error message about the wrong signal or “No input”. This error message can come and go at frequent intervals.

However, the computer with Windows 8.1 behaves almost the same as before. Warm start gives the same symptoms as Windows 10, ie no image. This is even if we visit the BIOS settings before proceeding to the operating system. However, we shut down the computer completely and then cold boot it starts the Windows 8.1 computer without any problems with DVI-DL overclocked to 588 MHz.

Minor issue under Windows 8.1

However, problems may still occur during Windows 8.1 if we sync the image again, for example by starting a game. In other words, it’s by no means a problem limited to Windows 10, although it’s not as troublesome under Windows 8.1. Under the older operating system, it is not consistent when it works and does not work.

To confirm that these problems only occur with the Pascal generation, we use a Maxwell-based Geforce GTX 980 Ti in the same test system. Both hot and cold start work with overclocking on both computers with Windows 8.1 and 10. The current driver for checking is version 368.39.

The conclusion is that those who want to overclock via DVI should therefore keep the old graphics card for a while longer. Nvidia’s Pascal graphics card currently has obvious problems with handling the concept.