Capacitors are polarized. They work better and last longer when you observe the plus and minus markings on the old ones, and install the new ones with the same polarity. The physical size is of no importance, but new ones may be larger and may not fit in the same space.
You can increase the capacitance in almost every case with no impact, and you can use a hotter heat range and a higher Voltage rating, but not a lower capacitance or a lower heat range or a lower Voltage rating.
WOW - I am so glad I just found this thread. I have the EXACT same weird issue with my 3.0ghz dual quad core MacPro2,1. It boots into safe mode only... in "non-safe" mode I get a duplicate cursor when I move it, then it turns into an endless beach ball at the grey screen after the Apple logo and just hangs. I was convinced it was the logic board, so rather than attempt at replacing it, I bought a new Mac Pro last weekend! I just swapped out the video card from the new Mac Pro (ATI Radeon HD 5770) and it booted up fine. Amazing! The price of a new video card is much less than $3,500. Whew.
Thanks so much!
For what it's worth, after doing some research I was actually able to repair my 7300GT. Turns out it's well documented that two of the capacitors on the board fail. If you have a soldering iron it's pretty easy to replace them. I'd never done any thing like it before and it worked out fine. I replaced the two capacitors and my computer booted up with no issues. Problem solved.
I'm curious. I made sure to get my 1,1 Mac Pro with the 7300GT specifically because it was the only video card that didn't rely on its own fan for cooling (I'd had fan failures on previous video cards). I've noticed that default fan speed vs temperature settings in the Mac Pro tend to emphasize quiet over cooling and so have consistently used smcFanControl to monitor and control fan speed to keep operating temperatures down. I only recently upgraded to a 5,1 6 core Mac Pro and never had the 7300GT troubles discussed in this thread. Is it possible that the capacitor failures were in any way related to temperature levels maintained by the default fan speeds?
The hatter wrote:
you are now using an ATI 5770 and the problems with lead contacts and solder and Nvidia that they had then and with the 8800GT.
Fans are great. So are double width cards. Built properly though, not like the ATI X1900 and others.
I special ordered the 5870 and have been concerned about both fan reliability (having had one fail on an SGI graphics card years ago) and the possibility of it clogging with dust, given that it's largely enclosed, but there's no longer any no-fan option.
In any case, could the higher temperatures resulting from quiet fan settings aggravate the deficiencies of those ATI cards?
These are the exact same issues I'm going through and it seems the original Nvidia GeForce 7300 GT card is the culprit. I don't have money for a new video card. It's the first thing I'm going to try to get my Mac Pro back.
Quick question to the original Poster of this thread. I did see the "mouse can move, but leavess a copy of itself" in the top left hand corner. Did you see a stripped dotted lines just hanging to the bottom right hand side of the curos itself? I posted a pic on my own thread.
I had the exact same problem that you had and fixed by deleting all the extention files from System/Library/Extentions. The system started up normally again.
I moved NV* and GeF* from /System/Library/Extensions
These were Extensions I removed
So the display RAM is working, and the primitive way of talking to the card (used by the diagnostic, by Safe Mode and when you delete extensions) is working.
When you put the card on "full speed, automatic" (which occurs on the Apple screen when the "loading" gear stops turning) the display stops working.
I'd say your card has probably had it, and you should look at getting a new card.
This card is no longer for sale as new. Don't hold your breath waiting for NVIDIA to issue any new extensions. And even if they did, it would not fix your problem.
I'm just reposting links - for information purpose only - what dust looks like.
I remember the first time I saw a G5 impacted with dust everywhere.
What six years can mean to a cpu heatsink:
PSU for some serious build up also