Backlight turns off when switching graphics on Acer laptop

[Nerdfighter]

I recently upgraded my Acer 4820TG from Win 7 to Win 8.1. Everything seems to be fine, but when I switch from integrated to discrete GPU, the backlight of my screen turns off. I know this because you can still see the screen very faintly, but it is VERY dim. However, if I plug in an external display, it's fine. The problem also disappears when I restart the laptop, and only occurs switching from integrated to discrete, but the other way around is fine.

Here are some important specs:

OS: Windows 8.1 Pro 64-bit
Integrated graphics: Intel HD Graphics (i5 450M), driver version: igdumd64 8.15.10.2900
Discrete graphics: AMD Mobility Radeon 5650M, driver version: atiumdag 13.152.1.1000

Has anyone had similar issues, or have any ideas why this occurs? Any input would be greatly appreciated.

 

[Wraith]

Has anyone had similar issues, or have any ideas why this occurs? Any input would be greatly appreciated.

Oh snap!! My Acer 8935G used to do this it the video controller that's at fault its a well known fault the only fix for me was to remove the MXM Radeon card and live without it. Acer are crap when it comes to support here you might have better luck than me they replaced my laptop twice but the fault remained.

 

[Nerdfighter]

Oh snap!! My Acer 8935G used to do this it the video controller that's at fault its a well known fault the only fix for me was to remove the MXM Radeon card and live without it. Acer are crap when it comes to support here you might have better luck than me they replaced my laptop twice but the fault remained.

Hmm, actually based on what you tell me, it sounds like more of a driver-issue. The card is obviously not broken, since it works after restart, or with a external monitor. The screen is also obviously not broken, since it also works after restart. Acer might be crap, but I don't think they would send you faulty units as replacement.

It's probably something driver-related, where switching GPU's also switches the backlight off. I guess unless anyone else knows how to solve this, then I'll have to try some different drivers. I mean it's not a serious issue, just somewhat inconvenient, so the worst case I'll just live with it.

 

[SPS]

Are you sure the screen brightness just hasn't reset?

 

[Wraith]

Hmm, actually based on what you tell me, it sounds like more of a driver-issue. The card is obviously not broken, since it works after restart, or with a external monitor. The screen is also obviously not broken, since it also works after restart. Acer might be crap, but I don't think they would send you faulty units as replacement.

It's probably something driver-related, where switching GPU's also switches the backlight off. I guess unless anyone else knows how to solve this, then I'll have to try some different drivers. I mean it's not a serious issue, just somewhat inconvenient, so the worst case I'll just live with it.

Acer never sent me faulty replacements they become faulty over time (a few months), they were a novel idea by Acer but lets face it either have onboard or discrete not both.

Check the Acer forums you'll see. Might even find my old threads were Acer support staff admit it's "A bit buggy" as the discrete AMD chip sets draw more from the PSU when switched which causes a voltage drop to other areas such as the CCFL back light tube. My laptop used to switch off when I tried switching it was a royal pain in the ass in the end I just pulled the Radeon out.. problem solved for me.

 

[Nerdfighter]

Are you sure the screen brightness just hasn't reset?

Nope, I've checked. I've tried to toggle brightness and backlight (there's a function key on my laptop for both), no response.

Acer never sent me faulty replacements they become faulty over time (a few months), they were a novel idea by Acer but lets face it either have onboard or discrete not both.

Check the Acer forums you'll see. Might even find my old threads were Acer support staff admit it's "A bit buggy" as the discrete AMD chip sets draw more from the PSU when switched which causes a voltage drop to other areas such as the CCFL back light tube. My laptop used to switch off when I tried switching it was a royal pain in the ass in the end I just pulled the Radeon out.. problem solved for me.

Interesting. The thing is, I never had this problem before upgrading to Windows 8.1. Before that I had used the laptop for 3 years and never had that issue. Must be something with the new drivers or Windows 8.1 that causes the voltage problem you described.

Well I guess I'm boned them. Luckily it's only an inconvenience, when it happens I can usually see just enough to save my work and restart the laptop, which fixes the problem.