I need to run 3 or 4 monitors

Standard RAM: 1 GB Maximum RAM: 32 GB*

Details: 1.0 GB of RAM installed as two 512 MB modules. 6 slots free. RAM must be installed in pairs, and for "best acoustic performance" contain an "Apple-approved heat sink".

*Apple officially supports a maximum of 16 GB of RAM but third-parties have been able to upgrade the system to 32 GB of RAM using eight 4 GB memory modules.

My experience has show that for all the RAM to be recognized correctly, they should all be the same.

You can expand the capabilities of the Mac Pro by installing cards in the PCI

Express slots. The Mac Pro has one double-wide PCI Express graphics slot and three PCI Express expansion slots.

The Mac Pro comes with a high-performance PCI Express graphics card in

slot one. This card contains the graphics processor unit (GPU) and provides

the computer’s display ports.

NOTE
Graphics cards from previous Power Mac G5 models are not

compatible with Mac Pro. In addition, Mac Pro graphics cards are

not compatible with Power Mac G5 models.

Each PCI Express slot has a 3.3 V and a 12 V power rail. On the 3.3 V rail, each

slot may use a maximum of 10 W. On the 12 V rail, each slot may use a maximum of 65 W, (not including auxiliary power through a booster cable), subject to the total wattage rules listed below.

When populating the four PCI Express slots, follow these total wattage rules:

Slots 1 and 2 (not including aux. power), max. slot power per slot 75 W

Slots 3 and 4 (not including aux. power), max. slot power per slot 40 W

All four slots (not including aux. power), max. total power 200 W

Max. aux. power per connector 75 W

Max. aux. power for both connectors 150 W

Max. total PCI Express power (slot power and aux. connector power) 300 W

NOTE
The combined maximum power consumption for all four PCI

Express slots must not exceed 300 watts (slot and aux. power) or 200 watts

total (slot power only). Before installing a card, check the manufacturer’s

specifications to make sure that it can operate in the Mac Pro, and obtain

the wattage of the device.