First time MorphOS user / intermittent blank screen…

[FigRoll]

I recently bought a Mac-Mini to install MorphOS, finally got to do it yesterday and it looks great!!

Boots-up fine and runs well apart from the screen goes blank for a second, then back to normal. This seems to happen at random times. It did happen occasionally with MacOS but not as often as with MorphOS.

The monitor is a Dell 24 inch (E248WFP) running at 1920 x 1200. It runs fine on Windows 7 and has never ever gone blank. I use a KVM switch, but have checked connected directly to the monitor and the problem stays. Have also tried different cables.

Any ideas would be gratefully received…

[itix]

I recently bought a Mac-Mini to install MorphOS, finally got to do it yesterday and it looks great!!

Boots-up fine and runs well apart from the screen goes blank for a second, then back to normal. This seems to happen at random times. It did happen occasionally with MacOS but not as often as with MorphOS.

The monitor is a Dell 24 inch (E248WFP) running at 1920 x 1200. It runs fine on Windows 7 and has never ever gone blank. I use a KVM switch, but have checked connected directly to the monitor and the problem stays. Have also tried different cables.

Any ideas would be gratefully received…

To me it sounds like the HW is broken =/ I would also check cables.

[Iggy]

Check tjhe monitor connections and the cable. This does not sound like a problem with your Mini. It sounds like a connection problem. If possible, substitute another monitor and see if you still have a problem.

[FigRoll]

Thanks for the responses.

I have taken the Mac-Mini to a friend’s house and tried on another monitor and its fine, the resolution there was 1280 x 1024.

The graphics card is a Radeon 9200 with 32MB Ram, is this enough Ram to work at a resolution of 1920 x 1200. I see in the ReadMe file 128MB is recommended?

[FigRoll]

Playing around a bit more… If I use the VGA input on the monitor it works fine…

[JuLieN]

Thanks for the responses.

I have taken the Mac-Mini to a friend’s house and tried on another monitor and its fine, the resolution there was 1280 x 1024.

The graphics card is a Radeon 9200 with 32MB Ram, is this enough Ram to work at a resolution of 1920 x 1200. I see in the ReadMe file 128MB is recommended?

You can easily check how much of your video ram is consumed :
right-click on the deepness-gadget on the top right of the main ambient screen. A menu will popup, called "modules", check the one called "graphicsmemory" (and all the other ones you think would be useful) and voilà :)

As for me, 1920x1200x24bits turned out to consume more than 50 of my 64MB of video memory, so I changed the screen's deepness to 15/16bits until I manage to flash a 256MB card :)

[amigadave]

As for me, 1920x1200x24bits turned out to consume more than 50 of my 64MB of video memory, so I changed the screen's deepness to 15/16bits until I manage to flash a 256MB card :)

I would guess that you are running out of VRAM and need to lower your color depth as suggested, or find a smaller monitor to use with your MacMini.

[Dragster]

I usually have the same problem with my 24" Monitor under OS 4.1 and MorphOS 2.6...when using a 1920x1200 screen on my Pegasos II. As far as I know, it's the DVI cable/connection... I think this can be solved by using a DVI-D DUAL LINK cable instead of a single link one... it has nothing to do with going low on video memory.

Hope that helps,

Cheers,

Dragster

PD. I read about that somewhere, don't take it as a fact, I haven't tested it myself!

[JuLieN]

@Dragster
Using the VRAM monitor I described above, I made some experiments and, when I overloaded the VRAM by opening lots of drawers and applications I noticed a kind of "swapping" effect : when I ran very low of VRAM (typically above 60MB used out of 64), I noticed a short freeze followed with a big flush of the VRAM that went back to around 40MB used, without me doing anything. I concluded from that that, for performances enhancement, MOS keeps a graphic copy of each drawer or application we open into its VRAM, even when masked, but flushes this copy if the original is not visible, when necessary. As a result it has to "rebuild" its layout when the drawer or the application is unmasked.
So yes, the more VRAM you have, the better :) Though, of course, you could certainly overload 256MB too. But setting my color-depth to 15/16bits kept my medium VRAM use under 40% all the time and I never suffered again from those short freezes that occur during the flushes. And FigRoll having only 32MB of VRAM I guess his high-resolution will certainly prove painful an experience.

[Dragster]

@Dragster
Using the VRAM monitor I described above, I made some experiments and, when I overloaded the VRAM by opening lots of drawers and applications I noticed a kind of "swapping" effect : when I ran very low of VRAM (typically above 60MB used out of 64), I noticed a short freeze followed with a big flush of the VRAM that went back to around 40MB used, without me doing anything. I concluded from that that, for performances enhancement, MOS keeps a graphic copy of each drawer or application we open into its VRAM, even when masked, but flushes this copy if the original is not visible, when necessary. As a result it has to "rebuild" its layout when the drawer or the application is unmasked.
So yes, the more VRAM you have, the better :) Though, of course, you could certainly overload 256MB too. But setting my color-depth to 15/16bits kept my medium VRAM use under 40% all the time and I never suffered again from those short freezes that occur during the flushes.

Interesting, but... the issue happens to me with a 128 MB ATI Radeon GFX card and I *never* force it to go below 70 MB of free vram which is still plenty... still the issue happens.

So, yours could be the 2nd reason for the monitor to blank at times... low vram... hope the original poster of this thread can find the right fix for his problem and share his experience with us.

I'll try the dual link dvi-d cable thingy sometime...

Cheers,

Dragstrer

[JuLieN]

@Dragster
I didn't suffer the blanking problem at all, just the short freezes when the flushes occured. But considering that FigRoll has half as many VRAM as I have but still use the same high-resolution (1920x1200) I can only guess that VRAM shortage could be for a big part of his disastrous user experience ^^
So reducing the color-depth is a quick fix. But there might be other reasons too, and your information is very valuable too :)

[FigRoll]

Thanks again for the responses…

After boot-up 18MB of video Ram is used, this is at 1920 x 1200.

DVI connections through the KVM or connected directly to the monitor blink, about one second of proper screen followed by three seconds blank, repeating… However using the DVI to VGA converter and connecting to the VGA input on the monitor eliminates the problem.

So, as suggested by Dragster I think it might be down to the cables, I will look out for some DVI-D Dual link cables and see if that will help.

[Krashan]

So, as suggested by Dragster I think it might be down to the cables, I will look out for some DVI-D Dual link cables and see if that will help.

What is the refresh rate of picture? If it is more than 50 Hz you can try to lower it. This reduces DVI bandwidth and may save you buying dual link cable.

[dfreniche]

Same problem here. Using DVI on my LCD TV/monitor doesn't show anything. Using DVI to HDMI same: nothing. Using DVI to RGB everything works like a charm.
Mine is a Mac Mini with 32MB VRAM. 15bit color depth, so 50% VRAM free. Will try the frequency trick.

If anyone knows the solution, please enligthen us!

[Iggy]

That is odd. I have My Powermac hooked to an LCD monitor via the DVI connector on my Radeon 9200 and I am not experiencing any problems.

However, if using the VGA input eliminates the problem, why not just stick with that? The video quality differences would be minor.

[Crumb]

Mine is a Mac Mini with 32MB VRAM. 15bit color depth, so 50% VRAM free. Will try the frequency trick.

If anyone knows the solution, please enligthen us!

You can disable "enhanced" display in all screens to save up some gfx ram (although I think newer versions have it disabled as default for gfx cards with few MB of ram you could disable double buffer too).

[dfreniche]

The problem exists from the very beginning. I've tried enhanced and normal. Still think the problem is with refresh frequency
Thanks for your reply

[FigRoll]

What is the refresh rate of picture? If it is more than 50 Hz you can try to lower it. This reduces DVI bandwidth and may save you buying dual link cable. The refresh rate is 50Hz.


I had a look around Currys tonight, DVI-D cable for £45!! (and I need two!!) Have bought two from Ebay, hopefully they will be OK.


However, if using the VGA input eliminates the problem, why not just stick with that? The video quality differences would be minor. Using the VGA connector would be a little bit of a pain as I use another two computers and the Mac-Mini through a KVM.


I will report back when I try the new cables.

Thanks to everyone for the input.