If your machine is still within 3 years of the purchase date, you can still get AppleCare. I bought my PowerBook without AppleCare. I needed to get a hard drive replaced but they said my service was expired unless I coughed up the money for an extra 2 years. Good protection if anything else comes up.
My brother's Mac Pro is a Dual Core 2.6GHz with ATI 1900, it was about a year ago, not that long, so I think you can get yours looked at. It costs the same now as if you were to buy AppleCare when you first purchased it, so check your receipt.
It sounds like you may have a defective video card, maybe they can replace it or exchange with a more recent model that would work with your system.
I have a 2006 Mac pro with X1900 XT card which was giving me the lines. Cleaning out stopped them for about four weeks, so I put an Accelero S1 cooler with turbo fans instead of the blocking up standard cooler.
I got lines once after this so decided my X1900 was damaged and ordered one of the new 2600HD cards. Put it in, worked fine except for disconcerting fact that the apple logo and cogwheel appear on my secondary monitor during start up. All OK when booted. Not quite as fast as the 1900 but much faster than the old 7300.
Knowing I had a viable back up card, I put the ailing X1900 back in and it has been fine for nearly a month now.
So your option is the new 2600 HD card which is cheap (£90).
Quite a few threads about using this in the "old" Mac Pro.
I don't know, and would be interested to hear what if anything 10.5.2 and the Graphics update have done for this combination. Everything above was 10.5.1.
If you are keen to stay with the X1900 the other option would be to get a new X1900XT. Very expensive (£390 from memory).
for this to make any sense you have to believe that there have been revs since the first ones (like mine) which have fixed the problems.
You could get the cheap 2600 for now and wait/hope that the 8800 becomes available for the old Mac Pro.
An Woodcrest/Clovertown Mac Pro compatible 8800GT may, or may not, be in the works. All we have to go on now are some remarks by an Nvidia PR rep and a purported response by the man himself, Steve Jobs.
I had quite a few system freeze-ups (at least once a day, often more) before I cleaned out my X1900.
One thing you didn't mention, but worked wonders for me, was to clean the GPU and heatsink with ArctiClean, and reapply some Arctic Silver 5 thermal paste to the GPU. Since doing that, I haven't had one freeze.
I upgraded to Leopard 10.5.2 today and did the Grafics driver update. Since then i am too experiencing freezes, lines and other gpu related abnormalitys.
This is definatly NOT a hardware problem, as i monitored the temp on tiger all the time and had a different gpu cooler with arcticsilver on the card.
Its not a solution for me to "downgrade" to a 2600 as i need the card for 3d work, and i too dont have Applecare ( the card has a new cooler anyway so is out of warenty i guess ).
I hope that a few more 1900 users file bugreports and call apple so maybe we will get a update.
Well, how do explain all of the people running the same OS, same hardware, same video card, that are not having problems?
Could small differences like multiple displays with asynchronous resolutions explain it? … Such as a 23" HD Cinema and a 20" Cinema plugged into the same machine? I think that could be one of the variable reasons some people do and others don't have the same issues.
Hardware driver bugs are quite unpredictable and hard to squash, which could be the reason Apple has not still addressed the ATI Radeon X1900 XT problems.
Sometimes hardware driver bugs may not necessarily affect all of the same build of machines. For instance, I've seen about 22 out of 50 Mac pro's exhibit the reboot from sleep problem while the rest don't in a Tiger running student lab.
Just my 2 cents.
When I had my 2.66 quad/X1900 I ran SMC Fan Control. I cranked my fans up to 1700 rpm, and had very little issues.
You could also pull one of these stunts...
Get a small fridge big enough to put the pro in. Drill a hole in the side of the fridge for cables, take a rubber plug, make a slit in it, run the cables through the plug and silicon the plug to the hole.
Fire up the Mac once inside and enjoy the most redneck cooling system ever though up.
Will keep your Mac Pro running nice and cool.
Hmmm intriguing idea.How about a kind of Russian doll affair.Get one of those mini fridges suitable for a can of brew put the laudable card in there then encase the Pro'ish in big fridge.
A more radical alternative is to move to Alaska/Antartica,run a power line from your igloo/hut and work outside.Hope this helps.
I sorry to say I have the same problem with my XT1900. I have cleaned all fans and I am working on a 67˚F environment to help. Cant play WOW or any of my Windows XP games without getting this problem. Started when I upgraded to Leopard. Done all updates, is driving me insane. Started looking for a gaming PC.........