I have intermittent trouble with TDR video failure but only at start-up (or coming out of sleep or hibernation).

I have the latest drivers (direct from AMD) and all memory, hard driver, dxdiag, graphics devices torture tester and general use all work perfectly.

This is a dual AMD Radeon HD 6450 video card 4 screen setup.

My observation is that the problem only ever occurs when Microsoft updates are being installed at start-up  (often on Wednesday morning!).

After restarts, it usually finally works and all works fine.

I would therefore like to try increasing the TDR timeout value in the registry to see if this 'cures' the problem.

https://msdn.microsoft.com/en-us/library/windows/hardware/ff569918(v=vs.85).aspx  gives registry locations, but these locations do not seem to be present for Windows 8.1.  Nor does a search for TDR and TDR* find any items.

Please can someone tell me where this timeout is for Windows 8.1.

Than

PAB

As it says in your link those should only be changed for debugging or testing scenarios.  DOing it in a consumer environment will likely not fix the problem AND may result in damage to the hardware.  It might be better to fix the reason it occurs in the first place.   SInce it only happens on boot or coming out of sleep I suspect a power issue.

You can use the following TDR-related registry keys for testing or debugging purposes only. That is, they should not be manipulated by any applications outside targeted testing or debugging.

The motherboard splash screen comes up correctly, followed by the Windows logo, and  if (and only if) the busy whirling balls indicator shows, then video_tdr_failure occurs sometimes.  It is my impression that the longer the update work, the more likely that failure will occur. 

I have high quality power supply that is more than ample for the hardware.  Everything else works perfectly.

So I have therefore no reason to suspect power supply limitations.  It seems more likely that a long enough time is being allowed for both cards and the four screens to get going?

Paul

By power I did not mean the total wattage the PSU can generate but rather a configuration issue in powercfg

My power plan is for very long power down times, so it very rarely returns from sleep mode, so I do not have enough experience with returning from sleep of hibernation to come to any conclusions on this.  I'm not even sure I have ever seem it failing from sleep/hibernation.

The very intermittent (and increasing annoying) problem is with startup from cold.

When it fails, it usually restarts, with illegible fuzzy screen on one screen, and a fuzzy pattern but with the video_tdr_failure message on another (and nothing on the others). Goes through varies checks (chkdsk?) sends error the MS and finally usually succeeds eventually after two or three restarts.