T400 screen blinks, goes black, then returns

[rsdown]

Hi & hope someone can give some guidance.

I have a T400, Win7Pro 32bit that has been acting strange. It is a problem that I sent it back for right after I got it, but now am out of warranty.

While using it (not at start up, usually has been running for a while), the screen will flash, then go completely black for a moment, then return to its previous state. Last night it happened while I was on the webcam, and I never lost audio only video. The computer does not give any indication that it is going to sleep. The previous times it has happened (all in the last three months), I did not lose anything I was working on.

I know this is terrible, but I am not sure which display this is. It only says ThinkPad display 1440X900. Location is on ATI Mobility Radeon HD 3400 Series.

I've been searching, and seen something about a switchable graphics problem. Could this be it? How would I correct that? Or am I looking at a dying something?

Thanks for any help you can offer.

Sam

[lead_org Microsoft MVP Contributor]

does this happen in the Intel GPU mode?

[rsdown]

lead_org,

Thanks for the reply, but I am not sure what you mean. I have never changed the video card mode, if that's what you mean. I rt click on the battery icon, go to switchable graphics, and the flyout says I'm set for High Performance, which I assume means I am using the ATI card. My Power Manager is Power Source Optimized (rarely use the battery. It has been plugged in for all these events). If there is some other information I can give that would help, let me know what you need.

[lead_org Microsoft MVP Contributor]

go into your bios menu and switch to the integrated gpu under graphics option and then retest.

If the problem stops occurring then it points to the ATI driver or hardware, if the problem persists then the motherboard hardware or the LCD is mostly at fault.

[rsdown]

Went into the bios & made the change. Had the option of switched, discrete, or integrated. It was set for switchable. Would it be worth it to try the discrete setting as well?

Since it is an intermittent problem, it may be a while before I can say that the problem is gone or not. I will check back for my next move when I narrow down the cause.

Thanks again.

[radiskull]

It is worth a shot.  If you still get a problem with it you wouldn't happen to have a spare monitor you can use to try and see if it still does it would you?

[rsdown]

Actually, I could work that out. Good idea. First I'll try this & see what happens. So far, it has not done it. Fingers crossed...