2006 Mac Pro 1.1 GPU Recommendation

[Foxbat]

I am in need of some NVIDIA Folding expertise and advice. I have a 2006 Mac Pro 1.1 with dual 2.66 GHz Xeon dual-core CPUs and the stock GeForce 7300 GPU. I switched from OS X 10.7.5 Lion to 64-bit Ubuntu 14.04 LTS to prolong its Folding life using the 7.4.4 Folding Client. Since the four expansion slots are PCIe V1.1, I know that even the 16x slot won't have the same throughput (roughly half) of a more modern motherboard.

I tried to run my GTX 750 Ti card (pulls all its power from the PCIe slot) but I had no video and no activity whatsoever. I put the old GeForce card into slot 4 and got video, but the GPU in Slot 1 was not visible to the system at all so it went back into its original home in my HP xw8200 workstation.

So my question is: what would make the best NVIDIA GPU to put in the Mac Pro 1.1 running Ubuntu, knowing that I can't feed the 16x PCIe v1.1 slot at more than 2.5 GT/s? I would think that I'd be wasting my money on a GTX 970 since I think the PCIe slot would be the bottleneck, but what metric should I be using to determine the best fit?

Thanks!

[PS3EdOlkkola]

The PCIe standards are mechanically and electrically backward compatible, with each newer standard updating the data transfer rate, line encoding and systems management, etc.

As you found with the 750ti, the card, it will physically fit in the slot. However, it's likely the power draw is greater than the PCIe 1.1 bus can supply from your motherboard. The 1.1 standard specifies 25 watts to be supplied by the electrical connectors on the motherboard in an x16 in the initial configuration with optional connectors adding 75 watts using a 6 pin connector and 150 watts with an 8 pin connector. So, that's the likely reason the 750ti card your using won't work is that there isn't enough wattage being supplied to the card through the 1.1 interface.

If the power supply on your Mac has a couple of 6 pin PCIe power connectors, you could try out a GTX 970 that has a requirement for two 6 pin PCIe connectors. I know the Zotac ZT-90101-10P has that configuration and the specs on it's website indicate it is compatible with PCIe 1.1 and it comes with the Molex-to-6 pin connectors in case your power supply does not have any available 6 pin connectors (not plugging Zotac, just that it meets the spec's).

In terms of performance, I generally see my GTX 980's take up about 33% of available PCI bandwidth (measured using Afterburner) on a PCI 3.0 x8 link. A PCIe 1.1 interface at x16 is spec'd at 2.5 GT/s and PCIe 3.0 at x8 is spec'd at 4 GT/s, and assuming no other devices are operating on your PCIe 1.1 bus, then using my GTX 980 as an example, 33% of 4GT/s is 1.32 GT/s, so your PCIe 1.1 should have the bandwidth to work with the GTX 970 without too much of a performance hit. However, additional improvements in data integrity and signalling between 1.1 and 3.0 will likely be responsible for performance degradation than just the raw transfer rate. In my own testing, from 1.1 to 2.0 to 3.0 on x4 to x16, I'd estimate about a 15% to 20% performance hit.

[Napoleon]

As you found with the 750ti, the card, it will physically fit in the slot. However, it's likely the power draw is greater than the PCIe 1.1 bus can supply from your motherboard. The 1.1 standard specifies 25 watts to be supplied by the electrical connectors on the motherboard...

I'm sure 1.x allows 75W total draw (3A*3.3V + 5.5A*12V) for graphics cards without optional connectors as well. You couldn't call PCIE2 and newer compatible with 1.x if it allowed only 25W while newer versions allow 75W. Source: http://en.wikipedia.org/wiki/PCI_Express#Power

On a side note, you want to take care when installing two "almost-75W" cards without optional power connectors. As it happens, the motherboard can't supply all that much power in the 12V line. Reason: the 24-pin motherboard power connector has only two 12V pins, max 6 amps each (12V * 6A * 2 == 144W). Source: http://www.playtool.com/pages/psuconnec ... #atxmain24
BTW, the legacy 20-pin connector has only one 12V pin...

Supposing two cards without optional power connector(s) draw the maximum 2 * 12V * 5.5A == 132W from the motherboard at stock, there isn't much room to maneuver. I wouldn't go overclocking such cards, for one. The motherboard connectors might not burn out immediately, maybe not even during the entire useful lifetime of the motherboard. Then again, they might. I wouldn't want to take such chances with stability and durability. YMMV.

[Foxbat]

Thank you for the reassurance regarding the data transfer via the PCIe slot, PS3EdOlkkola. I was able to find in other forums that people have been able to use the PCIe Power connectors on the Mac Pro 1.1 motherboard to supply a GTX 970 and are even running Yosemite using NVIDIA's drivers for OS X. GTX 970 cards are around $330 U.S. and the only reason I'd spend that much for the card would be to Fold with the card under Ubuntu. The Mac Pro-specific cables to connect to the PCIe power headers are under $40.

My other concern would be with feeding the GPU client with the one 2.66 GHz Xeon Core. I'm sure that will also exact a few percentage points performance hit, too, in comparison to a newer CPU. But my goal is to turn this 8 year-old box into something that can yield 3-4 more years of useful science.

I have seen there are rumors of new Maxwell-based cards below the 970 core count and price. I think I will wait a month or so and see if some new options appear.

[PS3EdOlkkola]

@Napoleon: Thanks for the reference to the PCI Express article. I was basing my comments on my experience after having built a multi-slot PCIe 1.1 x4 and x16 rig with Fermi GT430 cards back a few years ago. I was trying to find a low(er) power configuration to process Core 15 work units using passive cooling (less noise) and a smaller power supply was using a Foxconn motherboard. I could never get it to operate reliably. It turns out the slots, according to what Foxconn support told me, could only support 25 watts on the PCIe 1.1 x16 interface. I see that is true based on the article you referenced, but also true that the slots are supposed to support 75 watts after configuration. Anyway, I never got it to fold for more than 30 seconds before the box froze or blue screened. Consequently, I have a stack of GT430's looking for a good home

@Foxbat, I don't think the CPU will be much of a bottleneck if you primarily fold with the GPU. It's surprising how effective a plain vanilla i3/i5 can be in servicing a number of GPU slots quite effectively, so a prior couple-generations-ago Xeons should be just fine.

[bensch128]

@Foxbat,
I did exactly what you are thinking about. I threw Ubuntu14.04 onto an old MacPro1,1 , bought a Gigabyte WindForce2 R9 290X and got it installed.

My FAHBench stats are:

Explicit SP: 61.9 ns/day
Implicit SP: estimated ~767 ns/day before it nan'ed out

Explicit DP: 53.7 ns/day
Implicit DP: 691.03 ns/day

and my LuxMark scores are
Room = 1577
Sala = 2589

The trick to get enough power was to disconnect the SuperDrive and use both it's molex connects to give 150W (the 8slot PCIe connection) to the card. (The cable comes with the card)
The 6Slot connector is from the Motherboard. I'm pretty sure this is ok because every rail on the PSU is rated for 150W or higher and I don't believe that the harddrives share a rail with the superdrive.

It works like a charm. I once tried to overclock the GPU to 1500MHz Core/2000MHz Bus but X didn't like it.
I'm very happy with what I have now (1040MHz Core/1500MHz bus) and was worth every penny.

Cheers
Ben

[Foxbat]

@bensch128, more good news. I'm encouraged that my Mac Pro can make to past a decade of "continuous" Folding, and the combination of Maxwell efficiency and Apple's beefy Power Supply used for the Mac Pro bodes well.

[Foxbat]

I wanted to thank everyone again for their input. I picked up the EVGA GTX 960 SSC card from Amazon from under 200 USD and a couple of mini-PCIe to PCIe GPU Power Cables to feed the 12 V 8-pin PCIe connector on the card. After downloading the latest NVIDIA drivers, getting the current GPUs.txt from Stanford (it doesn't seem to want to download on my Ubuntu 14.04 boxes during th FAH Client Installation), and adding the GPU Slot to my Mac Pro 1.1 Client, I am now Folding Project 9411 (2696, 0, 28) at approximately 6m03s per frame. The CPU client is now down to 3 cores which means a drop in PPD of roughly 4,500 Points, but it's more than offset by the estimated 160K PPD from the new card!

(can you tell I'm smiling?)

[bruce]

... getting the current GPUs.txt from Stanford (it doesn't seem to want to download on my Ubuntu 14.04 boxes during th FAH Client Installation) ...

This is a known bug which will be fixed in the next client version.

[Foxbat]

This is a known bug which will be fixed in the next client version.

I figured I wasn't the first to report it; I'm just glad that I knew about it from the Folding Forum so I wasn't frustrated!

Looks like my Mac Pro will morph from a 10K PPD machine to over 170K PPD, for a little over $200. 17 times the science (I hope!)

[bruce]

Are you suggesting that you installed Ubuntu on your Mac Pro, or are you suggesting you managed to get the new GPU and its drivers to run under OSX?

[Foxbat]

I installed 64-bit Ubuntu 14.04 on my Mac Pro 1.1 as Apple stopped supporting it past OS X Lion. I burned a DVD-ROM and installed it on an old 250 GB SATA drive I had laying around. I had been Folding on this Mac Pro starting in April of 2007 using the beta client and then the Public Release of the various versions of the FAH Client for OS X. I recently replaced the Mac Pro with a new iMac w/Retina Display so I was free to experiment. The hardware (2 dual-core Xeon CPUs running 2.66 GHz and 10 GB of RDIMM) is still a solid platform, it just doesn't have the 64-bit EFI that Apple requires for their current OSes.

With this new GTX 960 card, I hope to continue Folding on this machine for another eight years.

[bruce]

That's an excellent way to use what is probably a dependable system for which the OS is no longer supported.

Is it going to have a power or heat problem, or does the GTX 960 generate less heat than the original GPU?

[Foxbat]

That's an excellent way to use what is probably a dependable system for which the OS is no longer supported.

Thanks, I was thinking of loading Windows 7 on it, but then I was reading here and elsewhere about Ubuntu 14.04 being supported on the 2006 Mac Pro so I figured I'd try it. The way Apple over-engineers the Mac Pro it should run for years.

Is it going to have a power or heat problem, or does the GTX 960 generate less heat than the original GPU?

The original card was a GeForce 7300GT and fanless. The new card has dual fans and the Mac Pro has four good-sized fans to promote air flow through the tower. The power supply can supply up to 300 W of PCIe power, and given the reduced power requirements of the Maxwell family of GPUs, it should be no problem.

[Foxbat]

One last update that might help someone wondering about the cost-benefit of my Mac Pro upgrade: My Mac Pro 1.1 is now generating an extra 1.2 million Points per week. I've tripled my PPD from my three machine Folding Farm with my $216 purchase. And that's with me throttling back my iMac 5K Retina w/4.0 GHz Core i7 to the lowest Folding setting since the fan was annoying on Full.

Thanks again to everyone who helped me take the plunge on the GTX 960.