Flat Panel interferance when second head at 85Hz?

[Ali]

Just swapped my Radeon out of my home rig, and put my trusty old G400 back in.

The reason for this is that I have recently received my nice new Dell 2000fp (20 inch flat panel), and still have my 20 inch CRT monitor (starting to get a little out of focus, thus the upgrade).

Now I notice that when I have the second head at 85Hz at any resolution the flat panel gets vertical lines down it when at a resolution over 1024X768. This fp has a native resolution of 1600X1200, but I normally run it at 1280X1024. (text get too small for my eyes if I run it at 1600X1200)

Ive checked the cables on both monitors, and they seem fine. The one on my CRT is a very high quality one, that has been serving me well for many years, the cable on the fp is the Dell one that came with it. Its quite fat, and has a ferrus cage (or what ever you want to call those cylindrical things around the cable) at both end.

Im using a very early 32Mb DH G400 as the video card. Both monitors are on a UPS, as is the computer itself.

Ive tried re-routing the cables so they are as far away from each other as possible, but makes no difference.

Im using winXP pro, with the latest beta drivers, and have tried both 'plug and play monitor' for the fp and the Dell 1700fp driver from the Matrox list, makes no difference. (there doesnt seem to be a 2000fp drive anywhere on the net that I can find).

Right now the fp is at 1280*1024*60hz, while the CRT is at 1152*870*75hz, but I notice the CRT flickering out of the corner of my eye all the time.

System specs that might make a difference:
Thunderbird 1400 (Water cooled, but not overclocked)
Gigabyte GA-7DXR motherboard
Crucial RAM 266mb
Very early G400 (first shipment to NZ)
onboard sound (also have Live!, but its on the shelf)
4X 60GXP hard drives, using onboard RAID controller
some SCSI stuff (in external box, turned off for testing)
D-Link NIC
350W enermax PS

Any help on fixing this would be welcome

Ali

[Ali]

Also just noticed, if I have SH set to 85Hz, and switch the monitor off, the fp still has the vertical lines. If I disable the SH in dispay properties, the lines go away.

Probably suggests its interferance in the card itself, not the cables.

Ali

[Greebe]

Do you mean disable dualhead (instead of SH) in display properties?

[Ali]

Sorry, I mean un-tick the box that says:
"Extent my Windows desktop onto this monitor."

When I do that the lines disappear instantly. That is of course when my CRT is at 85Hz (or above, just checked it at 800X600X100hz, and same thing).

Ali

edit: Stupid me, I meant 'Second Head' when I typed SH before, not 'Single Head'. Im just a lazy typist.

[Greebe]

When you check 'Extend my desktop onto this monitor' is the applicable subD connector termintated?

[Ali]

Im not sure I know what you mean.

The primary output of the G400 goes via a dsub cable to the dsub connector on the flat panel (which has DVI, dsub, composite, sVideo connectors.

The second output of the G400 is going via Coaxial? (those push and twist connectors, cant remember the name) to the CRT monitor, which has dsub, and those push and twist thingee connectors (the same as the old coaxial network plugs).

Does that help?

As an aside, I cant see your posts below to double check what you typed, only my posts. Whats up with that?

Ali

[Greebe]

Ahhh you're refering to a BNC cable

Does the FP have the interference if the monitor is turned off, yet with dualhead and 'Extend my Windows desktop onto this monitor' enabled?



Not sure why you can't see additional posts... browser issues?

[Ali]

Yep, as long as the second head (CRT) is set to 85Hz, there is interferance. Even if I unplug the CRT from the UPS, and pull the cable out of the back of the G400.

I had a couple of thoughts today at work.

im going to make up a grounding strap for the G400s heat sink, like the G450 have, see if that makes a difference.

Im also going to try raising the voltage on the AGP slot on my motherboard. I use to run the radeon at 1.7volts, up from the 1.5Volts standard, as I was overclocking it quite a bit (from 148Mhz, up to 210Mhz, its a LE version). I lowered the voltage when I put the G400 back in, because Im not overclocking that at the moment.

There is also that thread going about running a G400Max in a i845D motherboard. I might try the pencil trick from there, even though Im using an AMD760 chipset.

Im busy for the next couple of days (new wife, new office etc) so ill get back as soon as, unless you have any good ideas.

Ali

[Ali]

Ok, more stuff.

Tried upping AGP voltage. Made no difference, so put it back down

Tried earthing strap (using aligator clips) to both the main heat sink, and the little one which I think covers the TV out decoder (not sure whats under thre to be honest). Didnt do anything.

Tries unplugging the chipset fan, which is right next the the G400 for a while, didnt do anything.

I tried using the Xp 'Digital Flat Panel (1600X1200) driver, as both plug and play, and 1700fp drivers were causing the problem.

I noticed there is a choice of 75Hz refresh with this driver, so picked that, and problem went away. my fp does 1600X1200 at 60hz only, but if I run it at 1280X1024 I can up it to 75hz. That fixes the interferance problem with the second head.

I am now running the fp at 1280X1024X32@75Hz and the second head at 1024X768X32@85Hz and everything is nice again.

If I put the fp back down to 60hz even with the new driver (well, inf to be correct) the interferance comes back. Not that its a problem anymore.

Ali