"AGP driving value ( strenght )" BIOS option

[Malte]

Hi,
I´m just about to find out where this slight left-right jittering I recently noticed on my monitor comes from.

Since my Iiyama vision master pro410 and my G400 are in good shape some bad settings may be the source for the trouble. In some forums I read about the "AGP driving value" option the VIA KT133a has and I wonder if there´s any recommendation from Matrox what value should be used with a G400?

"Auto" sets this value to DAh on my ECS K7VZA mainboard. At

http://nathanpralle.com/writings/bios_settings_manual.html#AGPDRIVING

they say EAh should have been used...

I know I have to do some work to find the exact reason for this jitter, but just want to exclude a wrong value for this option as a source.

Oh, can using a value that is too aggressive cause the computer to refuse booting at all or is it still possible to get into the BIOS setup?

Regards,
Malte
(currently on XFree86 4.2 1152x864 at AGP 1x)

[UtwigMU]

http://arstechnica.com/guide/building/bios/bios-3.html

Check the BIOS guide.

For G400 and VIA KT, EA should be set according to above guide.


If the board refuses to boot, you can still clear the CMOS using jumper or boot using a PCI videocard (such as Millennium, etc.. that you can borrow or buy for 5€ online 2nd hand).

I did get crashes, when I set my AGP drive strength lower than default for Parhelia on TigerMPX (default is FA IIRC).

[Malte]

Originally posted by UtwigMU
http://arstechnica.com/guide/building/bios/bios-3.html

Check the BIOS guide.

For G400 and VIA KT, EA should be set according to above guide.


If the board refuses to boot, you can still clear the CMOS using jumper or boot using a PCI videocard (such as Millennium, etc.. that you can borrow or buy for 5� online 2nd hand).

I did get crashes, when I set my AGP drive strength lower than default for Parhelia on TigerMPX (default is FA IIRC).

Yes, this is one of the guides I have already read about this issue, so will give EA a try now ;-) What value do you need for your Parhelia? What mainboard/chipset do you use?

Malte

[Wombat]

It's not going to help you. Driving value has to do with AGP data transfer. That has nothing to do with the electrons that go from the video card to the monitor and onto the screen.

What you're seeing sounds like a failing capacitor in your monitor. Start saving up for a replacement monitor, or possible repair if you're lucky.

[UtwigMU]

FFh Tyan TigerMPX/AMD760MPX chipset

I'd also not blame the jitter on AGP drive strentgh. It's either a failing monitor or some kind of interference.

[Malte]

Originally posted by Wombat
It's not going to help you. Driving value has to do with AGP data transfer. That has nothing to do with the electrons that go from the video card to the monitor and onto the screen.

What you're seeing sounds like a failing capacitor in your monitor. Start saving up for a replacement monitor, or possible repair if you're lucky.

That´s what I have in the back of my mind and maybe just don´t want to accept ;-)

But, this jitter occurs very sporadical and doesn´t matter how many hours the monitor has been in use, so if it´s a failing capacitor, doesn´t it have to become worse and worse after some hours of use?

[Wombat]

Originally posted by Malte
That´s what I have in the back of my mind and maybe just don´t want to accept ;-)

But, this jitter occurs very sporadical and doesn´t matter how many hours the monitor has been in use, so if it´s a failing capacitor, doesn´t it have to become worse and worse after some hours of use?

Nope. There's no rule about how it would fail. It might stay how it is, it might get worse over time, or you might just try to turn it on one day and it will be totally broken.

[runderwo]

It could also be EMI or a ground problem. Try running the monitor (briefly) on a cheater plug to see if it is affected at all. Failing that, try taking an extension cord and plugging the monitor through it into a different circuit in the house. One of my friends had his A/C interfering with his monitor doing something similar to what you describe, and he ended up plugging his monitor into a different circuit to get rid of it.

[Greebe]

At first I'd also think cap, but intermittant EMI/RFI can also cause this... sorting it out is very difficult at best

[bsdgeek]

Yes, as they've said above check into the interference issue. I know I had a problem with jittering when I put my line conditioner too close to the monitor.

[Malte]

Originally posted by runderwo
It could also be EMI or a ground problem. Try running the monitor (briefly) on a cheater plug to see if it is affected at all. Failing that, try taking an extension cord and plugging the monitor through it into a different circuit in the house. One of my friends had his A/C interfering with his monitor doing something similar to what you describe, and he ended up plugging his monitor into a different circuit to get rid of it.

Thanx for that EMI hint... up to now I had plugged the monitor into an APC "surge arrest" E15 and will try it now without the "surge arrest" and in a different power socket. What I can definetly exclude is a bad VGA cable, recently got a very good BNC cable.

[rylan]

BTW video jitter usually originates from clock generator noise and DAC/output stage of the graphics board. Higher resolutions become more sensitive to jitter. What res/refresh are you running at? Oh and even though you got a new bnc cable, its still possible that can be the problem

[Malte]

Originally posted by rylan
BTW video jitter usually originates from clock generator noise and DAC/output stage of the graphics board. Higher resolutions become more sensitive to jitter. What res/refresh are you running at? Oh and even though you got a new bnc cable, its still possible that can be the problem

I´m only using 1152x864@75Hz and never been a hardcore 3D gamer, so my G400 has always had a calm life ;-) But the hint with changing the power socket may have helped... I had the Iiyama connected to an APC "surge arrest" E15 and have put the plug now in a normal power socket and guess what happened... no jitter so far for some hours... if the jitter will stay absent for the next 24/48 hours that may have been the reason...

[rylan]

Funky, might be something wacked with the surge protector.

[Malte]

Originally posted by rylan
Funky, might be something wacked with the surge protector.

Okay, this one is for the archive and APC UPS/SUrgeArrest owner who could be frightened after reading my suspicion...;-)

After some testing it´s now clear it´s *not* a power circuit problem, though it looked like one.

After some hours without the APC the jitter came back and the image made a "jump" to the right of the monitor. Now I tried the most obvious thing one could do when the image geometry is bad: adjust it - and it worked...

It really seems the monitor has just "forgotten" the saved geometry settings for the resolution I have used for so long... After adjusting the geometry the jitter has not returned. Though, I think there still might be some minor issue, because without any reason I doubt a monitor will ever just forget its saved settings.