[Q:long] How to fix: flashing hozizontal lines on G400 desktop

[Marunga]

Hello,
I have the same problem with my G100 in Linux.
But it works fine in W98.

Think maybe its got something to do with memory/chip timings.

Regards,
Marunga

[Sven]

I have found out a workaround to stop that flickering:

Underclocking the memory clock of the G400 to around 100MHz with MGATweak (Fo=252, MCLK=Fo/2.50).

This _really_ impacts 3D performance (in fact, the fillrate in D3DTest was more than cut in half), so it's just a temporary kludge for those of us who get sore eyes when staring on the monitor for several hours a day.

Apart from that, even aggressive SGRAM-timings (3,1,3,7,3,1,fast,1,1,1,0.0,0.0) or very conservative ones do not make a difference.

Matrox, are you reading this? We don't expect a "thank you" for troubleshooting your product, but I'd appreciate if you put this issue on high priority. Fix it. Fast.

Can anybody duplicate my findings?

Sven

[Sven]

Small addition:

There seems to be an interaction between the SGRAM-Optimization- and the MCLK settings. Just lowering the MCLK is not sufficient, only together with the SGRAM settings was I able to kill the flicker.

Sven

[jms]

Sven,
Setting the acceleration in display properties to some acceleration removes the flicker, but this effectively kills performance.
I took the card back to the shop where I bought it earlier today. They tested it and said it was defective. Unfortunately they didn't have a replacement card, so I will not receive this before tomorrow. But they had tested other G400 in the same machine before and hadn't seen this redraw problem before...
I will let you know if the new card is better when I get it tomorrow.

Jan M.

[jms]

Hi Sven,
I took the card back on monday, and received a new G400 16MB Singlehead yesterday. The card had the exact same problems as my first one. Feeling pretty frustrated I returned to the shop. After talking to them I decided to shell out the difference for a 32MB Dualhead.
I returned home and installed it, and now everything works perfectly(no flickering what so ever).
The two Singleheads I had, had quite different serial numbers JBKxxxxx and Kxxxxxxx(can't remember exactly).
My new card works perfectly in Win2000 RC2 as well.
I hope you find a real solution to the problem. Maybe all 16MB OEM Singlehead are crap?
-jms

[syrios]

Sven,

I can verify that the mclock / sgram settings you mentiones work. The flickering stopped but the 3d perforamnce dropped as expected. I emailed 2 days ago matrox technical support and I'am still waiting an answer(beyond a message asking for IRQ settings). I was about to return my card for a new one but after what JMS stated I am going to wait for a couple of days for a solution from matrox and then go buy a Voodoo3 3000 (I' am not going to pay extra maney for a 32 MB / dual head card)

[Sven]

Syrios,

thanks for verifying my findings. I have received a reaction from Matrox support Germany (which wasn't half as pointed as many of the suggestions in this forum), and in my reply directed them to this thread. We have done a great deal of troubleshooting that they should have done long ago.

In turn, I expect a clear statement whether this flickering is due to a hardware error or a driver problem. I the latter case, if the upcoming driver release is not going to fix that, I am considering returning my card.

Whether it will be a Matrox card or not is largely determined by their efforts to fix the problem. Matrox: Act now, or you are going to lose some loyal customers (and multipliers).

Bye, Sven

[jms]

Sven,
I just noticed that my new G400 Dualhead has taken IRQ10 where as I'm quite sure it was IRQ5 that was used with the Singlehead. Strange indeed, but this probably affects the problem? Maybe the cards I returned wasn't defective after all, allthough the first one was tested in a PC in the shop I bought it in. Maybe you should try to shuffle those interrupts?
Bye,
jms

[SteveC]

NEVER give a matrox graphics card an IRG below 8. It is known to cause problems.

------------------
Cheers,
Steve

PS: Some or all of the above message may be wrong, or, just as likely, correct. Depends on what mood I'm in. And what you know. ;¬)

[syrios]

Sven,
I doubt that it is a friver-related problem beacause the flickering seems to appear even if the driver is removed (with matrox tool) and the card is installed as ''PCI-VGA cimpatible adapter''. In this case you cannot go higher than 640*480*16 colors but I think that I can see the flickering there too.
I will try a clean w98 install to a spare HDD and assign IRQ10 (now its 11) to my G400.
If I get any results I'll ket you know...

[Sven]

My system is so packed, I'd rather not shuffle my IRQs around. Last time I tried, it took my quite some time to arrange everything back. Okay, I should set a new hardware profile first. Okay, I could predefine one in my CMOS-setup.

BTW, the Millennium is at IRQ 15, together with its IRQ-Holder. I did not find anything related in the manual (how come I'm not surprised

Thanks for your ongoing support,

Sven

[Sven]

Man, those support guys have a strange attitude. That's all they told me via email (translated from German):

"Thanks for your information, it would be best to contact your dealer".

Is that stupid or what? We have around ten people with the same problem here and in the other ngs, and they're not even trying to reproduce it, let alone solve it?

Still shaking my head,

Sven

[Sven]

Update:

I have exchanged my G400SH 16MB OEM for a G400DH 32MB OEM.

No more flicker. No more downclocking. No more hassle.

It really seems to be a hardware issue. Matrox Support Germany was completely clueless.

Thanks for your support!

Sven

[sasulj]

I am going crazy with this problem. So I went to store and tried three cards: g400 32mb DH, and two G400 Max 32mb DH, on three different systems : MSI-s motherboard 440bx, celeron 466;via chipset motherboard, celeron 500; Abit BE-6, P3 500;,with three different monitors. I've tried all combinations and there STILL the lines were there, and I don't know what to do with this flickering any more. Any new suggestions?

[The PIT]

sasulj. Doesn't that say to you something like dodgy monitor or electro magnetic interferance in your room/building.