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MP 1,1-5,1 Would you buy a turnkey, non-destructive Pixlas Mod? (poll)
- Thread starter mattspace
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I would so be all over this.
I am also in Aus. Have a Mac Pro 5,1 with an RX580 installed - powering that off the 2 6 pin Mini-PCIe ports only to discover one of them doesn't actually work. There is enough power from the 1 working however but I am wary of overloading that and bricking my logic board.
Had the same thought as you - would it be possible to have some kind of passthru adaptor the you connect the power supply connector to - run the "extra" power cables out of that and then the other end plug into the logic board connector (like the existing power supply connector).
Spent (quite) some time identifying the existing plug/socket make/models but couldn't find anything (off the shelf) that looked like it could be used.
I ended up buying a 2nd hand power supply - and a dead Mac Pro where the power supply still ok - and have applied the Pixlas mod the the spare bought (logic was that, if I messed it up, I could just put my currently working PS back in).
I would still prefer a reversible solution like you describe, so if you do come up with something, I am all in.
I am also in Aus. Have a Mac Pro 5,1 with an RX580 installed - powering that off the 2 6 pin Mini-PCIe ports only to discover one of them doesn't actually work. There is enough power from the 1 working however but I am wary of overloading that and bricking my logic board.
Had the same thought as you - would it be possible to have some kind of passthru adaptor the you connect the power supply connector to - run the "extra" power cables out of that and then the other end plug into the logic board connector (like the existing power supply connector).
Spent (quite) some time identifying the existing plug/socket make/models but couldn't find anything (off the shelf) that looked like it could be used.
I ended up buying a 2nd hand power supply - and a dead Mac Pro where the power supply still ok - and have applied the Pixlas mod the the spare bought (logic was that, if I messed it up, I could just put my currently working PS back in).
I would still prefer a reversible solution like you describe, so if you do come up with something, I am all in.
Hi
@mattspace
I know that I can use safely use more powerful Geforce cards on Linux/Windows and ATI for Mac if I have the Pixlas mod and OC.
@tsialex mentioned this option.
What kind of combinations of graphic cards can I add if I have the Pixlas mod and OC?
Probably, I can't expect that I will add AMD Radeon RX6900 XT 16 GB GDDR6 for Mac and Nvidia GTX Titan X 12 GB for Linux/Windows.
What are the technical limitations for Mac Pro if we want to use the Pixal Mod with the combination of two graphic cards?
What combinations of the newer graphic cards (NVidia and ATI) start to get dangerous for Mac Pro with the Pixlas mod?
@mattspace
I know that I can use safely use more powerful Geforce cards on Linux/Windows and ATI for Mac if I have the Pixlas mod and OC.
@tsialex mentioned this option.
What kind of combinations of graphic cards can I add if I have the Pixlas mod and OC?
Probably, I can't expect that I will add AMD Radeon RX6900 XT 16 GB GDDR6 for Mac and Nvidia GTX Titan X 12 GB for Linux/Windows.
What are the technical limitations for Mac Pro if we want to use the Pixal Mod with the combination of two graphic cards?
What combinations of the newer graphic cards (NVidia and ATI) start to get dangerous for Mac Pro with the Pixlas mod?
There are two basic limitations, power and space. Two modern high end GPUs, even if the 980W PSU can power both, are limited by the space available inside the Mac Pro. It's not just the space for the GPU itself, but the space necessary for the fan to get adequate amount of air. The GPU heatsinks need some space between the fans and the next card PCB to get adequate volume of air or the GPU will overheat.
If you find two modern GPUs that do not have excessive power draw and are only two slots wide you can make it work, like the very expensive Radeon Pro W6800 or some rare 6800/6800XT, but even mid-end GPUs today are slightly wider than two slots. There is also the length problem, with several GPUs requiring the relocation of the PCIe fan assembly to give space to the GPU. Modern oversize GPUs are a problem even for 2019 Mac Pro.
Another thing that can give headaches is macOS being aware of a GPU without drivers, I had several KPs while testing a GTX 2070 and a RX 580. Other people had more success, so, depends on the combination of the GPUs. This is another thing to be aware and you will probably need to disable the PCIe slot where the GPU without drivers is installed via OpenCore.
Even if is possible to do what you want, you have to think if it's not more economically sane to get a used 2019 Mac Pro or even a dedicated slave PC for rendering. While high end GPUs are not cheap, Radeon Pro GPUs are insanely expensive even second hand.
Another two things that I forgot to write about, missing AVX instructions and limitations of the PCIe v2.0. A lot of apps are starting to require AVX instructions that MacPro5,1 Xeons do not support and that the PCIe v2.0 constrains the performance of modern GPUs.
So, you have to evaluate if it's reasonable to invest with a nowadays very limited platform.
I think the W6800 requires you to be running one of the later Big Sur releases. Do you intend to stay on High Sierra? As I'm sure you know, Aperture can be patched to work on Catalina and later though.
That's about the shape of things - depending on what happens with WWDC. OC to Monterey, then look for lifeboats.
I’m very interested in the non destructive pixlas mod idea. I currently have the RX580 on a shelf, a vega 56 in the machine running on a powerlink, but I have had a couple of gaming incidents where it goes to full fans and hangs, or powers off.
it’s either a thermal event that the card is unstable, or it’s drawn too much power. either way, I’d like to modify the machine to pixlas to be able to flash to 64 with this card if it can be proven stable, or get a later better card.
it’s either a thermal event that the card is unstable, or it’s drawn too much power. either way, I’d like to modify the machine to pixlas to be able to flash to 64 with this card if it can be proven stable, or get a later better card.
Sadly, I don't have a working cMP any more - so I'm not pursuing the project.
For anyone who wants to pursue it, the basic premise of the design was to create an inline passthrough plug that the power cable plugged into (it’s a standard plug), with a PCB that took a power feed off to the side to standard GPU molex connectors, while returning the main power to the motherboard with the standard connector.
Does it need a PCB? Could it just be male and female plugs connected by short lengths of wire, with the cables for a PCIe power connection doubling up on some of the pins? Like those fan adapters that split off from a Molex extension. Or are the cables too thick for that?
Come to think of it, just a short 'power extension' cable could be useful, as the Pixlas mod could be done to that, on the bench, rather than having to splice into the original PSU wires. Easier, safer and 100% reversible.
Come to think of it, just a short 'power extension' cable could be useful, as the Pixlas mod could be done to that, on the bench, rather than having to splice into the original PSU wires. Easier, safer and 100% reversible.
That's pretty much what it is, but the folks I was having scope out the design had suggested that it was easier from an electrical and manufacturing point of view to have a PCB handling the diversion, rather than trying to connect every single wire.