Additional video card on Mac G5 Quad

[matetod]

Hi guys,
I have a curiosity:

I have seen in some screenshot on the net people use additional old generation video cards (along with the original),
I currently have a R7- 240 OEM (technically a rebrand of the HD 8570),
I mounted it on my G5 Quad (beside the original Geforce 6600), it is recognized, "lspci -v" indicates me the "radeon" modules loaded, but does not emit any video signal.

If I start the PC with the video cable connected to the R7-240, (with my Geforce 6600 installed) the PC seems to start (keyboard and mouse light up) but after a few seconds the fans go at max with the black screen, in this case on both video cards.

Is this really possible, even if with some other video card? I miss a few steps to allow it to emit video signal?

Thanks in advance
Matteo

 

[Tratkazir_the_1st]

R7- 240

Card already works in any other computer?

 

[matetod]

Sure is my old card, tested right before install in Mac, don't work on Debian, Fienix, Void, and some hour ago trying on Lubuntu Remix work only in shell mode after several reboot and update (but this update broke X11/Xorg and LightDM).
Now I'm on Void XFCE with all update and don't work.

 

[bd129]

Hi,
I've gone about it by blacklisting nouveau (and possibly another driver too). I can't remember if I also have a custom x config, but I don't think so. This makes the kernel initialise the AMD gpu.

To get grub to boot (at least in the default config) you have to have an Open Firmware graphics card enabled at boot, without it it'll do as you're seeing. What I do is plug the noVideo card into a spare port on my monitor - which also makes it easy to jump over to os X.

 

[matetod]

I absolutely do not expect the boot screen to be visible to me, I was aware of this limitation.
But I remembered that among the modules for GPUs on PPC64 there was some limitation, I often see around the R5-230 or in general the old TeraScale architecture and variant 2.
I do not remember which were for nvidia GPU.
I will try to blacklist the nouveau module in the meantime.

 

[bd129]

>I absolutely do not expect the boot screen to be visible to me, I was aware of this limitation.

I'm not sure you quite understand. In the default config at least, grub will hang and not boot, unless you have an active OFW compatible GPU.

 

[dextructor]

@z970mp big endian systems will work with any AMD/ATI card that's older than GCN, i.e. TeraScale architecture and older (i.e. HD6000 and some specific 7000/8000 and older, though most 7000/8000 were GCN)

my testing G5 has an R5 235 (which is basically a rebranded and somewhat overclocked HD 6450), which is about as good as makes sense in that machine - plus it's single-slot so it won't block a second internal PCIe slot, you're likely to fill them anyway, you have 4 and you need... the original GPU, the modern GPU, perhaps a USB3 controller, and maybe a PCIe M.2 SSD, that means none of the other slots can be blocked

nvidia is likely to be a hit and miss, because of nouveau bugs; even AMD is going to be relatively buggy in some places, but at least stuff like video and a lot of games will work fine

on little endian systems, any AMD card, e.g. I'm running an RX 5700 XT right now

The Void Linux developer @q66_ answered this... If you card are GCN than no go on Linux and if Wikipedia aren't wrong (https://en.wikipedia.org/wiki/List_of_AMD_graphics_processing_units#Radeon_HD_8000_series) your card are GCN1

 

[matetod]

Now with some power trick i'm trying with a HD5970 but don't work too (because is a dual GPU?), after blacklist nouveau the module said some like:
radeon: 3D acceleration error
And Xorg don't start, i have only a black screen (instead of a no signal screen).
Can all Terascale (and 2) architecture GPU run? In what way, what i miss?
Thanks

 

[bd129]

Hi,
So - I'm running a HD 8490 / R5 235X (Terascale 2) in the 8X PCI-e slot. My Grub config (/etc/default/grub) is attached, and I just checked and can't see anything custom that should make a difference in my x config (it's mostly auto generated stuff). The 5970 should work.

Cheers.


Ps: I'd get a smaller GPU if I were you - @q66_ is spot on in the slot usage comment. The 235 I have was only about £12.

 

[matetod]

Hi,
actually i'm seeing for a AMD Radeon HD 6670 (28 euro) or a more powerfull FirePro V5800 for 34, that are without any power connector and single slot and Terascale 2, the FirePro is the powerfull card without power connector.

I can't find in my country 235 at this lower price, i find for 25/30 euro, for that price i prefer one those.

 

[Tratkazir_the_1st]

A bit of advice. You can edit your /etc/default/grub, to make it more useful & convenient.
GRUB_DEFAULT=0 -> GRUB_DEFAULT=saved
Add line "GRUB_SAVEDEFAULT=true" (This 2 lines works as it's written, literally - if you're starting from Advanced options & select non-default kernel, for example). Also remove this: "loglevel=4 slub_debug=P page_poison=1", as written in Void's wiki, this causes performance penalties on PowerMacs. (Ok, loglevel is other thing, I just prefer to see EVERYTHING what system displays at startup ). Don't forget to update grub config with "update-grub" command .