Installing 2 Radeon HD5870 cards in a Mac Pro 2010

Introduction

Performance

To validate performance levels, we used 3DMark Vantage.

First, results from the Mac Edition cards overclocked at 910/1300 (installed alone in the Mac Pro)

With the new Mac Pro 2010, it is now possible to install a Radeon HD5770 graphics card enabling the management of up to 6 displays simultaneously. However, this solution is not available for the currently most powerful graphics card in this series, the Radeon HD5870. The latest is about twice as fast as the HD5770, but it also drains much more power, and it requires two 6-pin PCIe power lines from the Mac Pro motherboard.

But what could be the use of such a setup with 2 fast graphic cards?
It is true that not everyone would need it, nor could even benefit from such power at anytime, however, hereafter are some examples:

• Manage simultaneously 6 monitors;
• Be able to use 2 Open CL units for GPGPU-aware applications;
• And last but not least: Activate the Crossfire mode in Windows for playing Crysis-like games at max settings and resolution after a long and hard day of work on a Mac Pro.

To install a second HD5870 in a Mac Pro, the following problems will have to be solved :

• Find a way to power the second card without putting the Mac Pro PSU in danger;
• Carefully monitor the temperature of the 2 graphics cards, the resulting heat released and the potential noisy side effects;
• Successfully activate the Crossfire mode in Windows (prior to the latest Catalyst drivers, the Radeon HD4870 Mac Edition could not be used in Crossfire in Windows; is it still true for the HD5870?).

In this article we will describe our solution for our available hardware.

Let’s start with materials and components that we will be using:

• 1 Mac Pro, here a model from 2006, Hexa Core (Xeon W5680@3.33 GHz), sporting 24 GB of RAM (3x8GB), 2 x 1 TB HD and 1 OWC Mercury Extreme Pro SSD of 200 GB installed in the Optical bay. It also includes a Radeon 5870 Mac Edition. So, a configuration with already rather high power consumption, and a PCIe/SATA compartment already well used.
• 1 Radeon HD5870, here an XFX HD5870 flashed with an EFI EBC hybrid ROM. This card is based on a rev2 PCB, so it is different from the ATI/AMD reference design, and features a shorter PCB. This can be important, as we shall see later.
• 1 power adaptor SATA to Molex.
• 1 Molex type extension cable in ‘’Y’’.
• 1 power adaptor Molex to 6-pin PCIe.
• 1 Crossfire bridge.

This is the list of materials that we used with our settings and configuration, so in other conditions it might be different. In theory, any Mac Pro is able to host 2 graphics cards, with some limitations for the Mac Pro 1,1 due to its PCIe cables. Similarly, an owner of a 12-core Mac Pro clocked at 2.93 GHz with all its disk bays in use will have to be careful about the real power still available from the PSU for a second graphics card; while a Mac Pro 2008 with only one SSD in the second Optical bay should not have to worry too much regarding power consumption. Last but not least, the way the HD5870 is designed concerning its cooling system is important too.

After hardware components, let’s list applications and software required for this test:

• Mac OS X
• Windows Seven 64bit on a Bootcamp partition, with the latest Catalyst drivers installed (10.9)
• Techpowerup GPU-Z
• MSI Afterburner
• Ozone3D Furmark (an .exe file to be renamed etqw.exe to be able to use it in Crossfire mode)
• Futuremark 3DMark Vantage
• Techpowerup ATI RBE

We are now ready to start.