Suggestions for a Graphics Card for my Mac Pro (Early 2008)

Regardless of whether it has everything it needs to run a display, it should NOT beginning you the symptoms you reported if it is intact.

The fans go to maximum when the fail-safe circuits show it is being ignored, or the System Management Controller SMC has crashed. Is this the fans on the card only, or ALL the fans in the Mac?

A note for Users who would like to push their 2008 MacPro 3,1 all the way to Mojave using hobbyist hacks:

• Early-2008 Mac Pro (MacPro3,1) GPU support: When running Mojave, you CANNOT use a newer AMD video card EVEN IF it is a Metal-comptible card and is supported in Mojave. The newer AMD drivers used in Mojave require the SSE4.2 instruction set, which the MacPro3,1 does not support. There is no way around this at this time. Your only GPU upgrade options for MacPro3,1 systems are nVidia cards, which work perfectly fine. 

Did the NVIDIA GeForce GTX 560 Ti 2048 MB every work?

For cards see:

new graphic card for Mac Pro 2008 3.1 - Apple Community

Man alive ! That looks like a beast of a card. They both do.. when i checked out the specs for the RTX 2060 my jaw nearly hit the floor. Of course, the 1060 and 1070 Ti’s are no slouches either. Pretty slammin’ overall. No video? Hmm.. don’t have Boot camp or windows 10 64-bit installed on my mac pro. No windows installed, really, not any flavor of windows. Much like the time i grabbed a ton of taco bell’s finest food , doused liberally in their hottest sauce, eaten in a hurry because i had to be somewhere fast, we were running late, i thought i could handle it, well i was wrong and much like me trying to get boot camp going and installing windows on my mac pro, it ended—badly, very badly. That being said, the physical requirements are for a dual channel pci express slot x 16 and i don’t think a 3,1 mac pro has that, but i could be wrong.couldn’t really be the power requirements, and i’m guessing you installed the latest drivers + software for the RTX 2060 from nVidia. So, i’m out of ideas on that one

jb

You said " Tried a GTX 2060 ". Did you mean "RTX 2060"

Yes, it's an RTX 2060--sorry.

Hi there kj8 maybe I can help you. You may be right, your card might not be 100% compatible. Looks like it should be though- at least technically. And you have el capitan. About the only way to make it compatible would be to flash it- no, i sure don’t know how to do that -you’d have to contact a company/person who does. There’s also the question of PCI bandwidth/speed. A 2008 mac pro doesn’t have the same bandwidth/speed as, say, a 2010-2011 mac pro. At least for the PCI slot. The only video/ graphics card I know works in the 2008 mac pro is the Radeon sapphire 7950 mac version, which is the one I have now. It has 3 gigs of video ram and does mini displayport and hdmi. I’d suggest making sure that your video card’s power supply cables are plugged into the logic board( there are two 6-pin molex sockets there) . Other than flashing the card, and the sapphire suggestion, there’s not much more for me to say. I’d suggest doing the good ol’ reset smc/pmu and zap pram, maybe dusting out the card with compressed air... the only nvidia driver i know of is for the quadro k 4000( maybe 5000?) so maybe try that. A long shot...

try this :

https://www.insanelymac.com/forum/topic/309363-solved-nvida-gtx-550ti-in-el-capitan-10112/

john b

I am running an Nvidia Geforce GTX 1060 SC on an early 2008 Mac Pro 3,1 under Boot Camp and Windows 10 64-bit to run games. It only requires one mini-6 to 6-pin cable from the motherboard to the card. Gets about 110 FPS under the Heaven 4.0 benchmark. Works great for CoD Infinite Warfare and CoD WWII at low settings but it's just OK for CoD Black Ops 4. Runs much like D500s on a Mac Pro (2013). Tried a GTX 2060 with a dual mini-6 to 8-pin cable under Boot Camp in the MP3,1 but no video--don't know why since it only needs 160W and it's getting 225W. Will keep trying.

Thanks Johnb-one. It could be a driver issue although I thought Windows would use generic M$ drivers on first boot and then I could get the RTX 2060 drivers from EVGA, at least that is what happened when I first booted with the GTX 1060. Strangely, I get the start up chime with the 2060 and it seems to be booting but I get just a black screen and a monitor message of no displayport signal. I may also try using a DVI-D cable instead of a displayport cable.

The MP3,1 has two 16-lane PCIE 2.0 slots and two 4-lane PCIE 1.1 slots. I don't know about dual channel on the 16-laners, however.