Q: About old Mac Pro

Good heavens-- Questions  Questions !

I'm no expert, and have nothing to do with Apple, apart from using and loving my Mac Pro (of course) but I'll do my best to help you out, as this is a user-to-user forum.....

1-Yes, the later machines may have a bit of a performace boost and have faster PCI-Express slots. In any event, going from a  2006/ 2007/2008 Mac pro to a 2010 or later one, you may notice a difference

2-I guess so, I got a used 12-core Mac pro, and I don't even use Adobe stuff that much. Also, graphics card, processor speed, and amount of RAM on board may play a part in how well Adobe stuff runs ( I presume you're talking about the graphics manipulation applications and not  the pdf reader), for me it was get the biggest bang for your buck you can.

3- I've never had any problems or issues due to its age.  as I mentioned before, I bought it used, and it's been fine. My only gripe is that the wifi card is 802.11 n and not 802.11 ac, so it's kinda slow

4-that's a good question. I don't know, maybe check out barefeats.com or talk to someone who has compared one to the other.  I think the smallest CPU you could get now-a-days would be Quad core, but maybe 6 core are more common

5-pretty quiet, at least mine are. If you have loud fans, like, really loud fans, then maybe they should be replaced

6- Don't know that one for sure either.  Are you asking if it uses all 980 watts  as it is, or does it have some in reserve?

I'd say it has some in reserve, unless you have a ton of things plugged into it inside.  About the only advantages I could see for having an iMac 5k would be the 5k, it would have a screen build in, and fast wi-fi and if you were worried about a graphics speed boost, you could probably get an eGPU (that's an external Graphics Processing Unit) that you could install a beefy video card in, and connect via Thunderbolt. Of course, all of this stuff, the iMac 5k, RAM etc, and the eGPU would probably cost you a good bit as well. How much? I have no idea

so, I hope I have helped you sorta weigh up your options,  Sunshine 7913. Yes, you can buy Mac Pro's used from a reputable person and they'll work fine, probably

good luck (whew !)

John B

- Note that the firmware for the 2099 can be updated to that of the 2010 Mac Pro.

- Regarding GPUs, you are limited by getting drivers. For some new graphics cards Mac drivers are not yet available. You also may be limited by the power supply if you install more than one graphics card. If you need more power users have install a second PC power supply to supply the AUX power to the graphics cards.

- The memory speed on the 2010-2012 (and 2009 with upgraded firmware and a CPU that uses 1333) operate at 1333 if compatible memory is installed. The 2010-2012 MP uses triple channel memory so if you install three modules you can slightly faster memory access than if 2 or 4 modules are installed.

It is a tradeoff for filling all slots to get more total memory or leaving one slot (two if dual processor) empty to increase memory access.

- Using PCIe cards depends if you can find compatible Mac drives