Maximum render size (print res)

Mon Apr 20, 2015 8:44 pm

glimpse wrote:
honestly - that's the best thing bout GPU render engine - especially if You have several cards on Your machine - You can render in the background without any interuptions =) & the only thing You notice is a warm breeze through Your feet =) as for PS & other programs You can still use GPU acceleration if You have discrete GPU =)

I didn't even consider that, so its a very pleasant bonus. Titan is a bit noisy though, will have to sort that.

Maybe I spoke too soon, the Titan is VERY hot. The back of my Mac feels toasty and inside it's...well hot. Bit concerned as the fans are not pickup up speed to compensate...

Mon Apr 20, 2015 8:50 pm

sdanaher wrote: Maybe I spoke too soon, the Titan is VERY hot. The back of my Mac feels toasty and inside it's...well hot. Bit concerned as the fans are not pickup up speed to compensate...

X is not noisy if it has enough airflow - so try to think of a mod how to provide more air into You GPU compartment =) so those cards would not be choked..nvidia designed this card to have pleasant acustics & left quite a lot of headroom for OC too..-if it's more than 80C You have some airflow issues..

Mon Apr 20, 2015 8:57 pm

Welcome to the world of PC modding eh?

Hmm I had the 980 and ATI 5870 running in the Mac with no problems in the same slot locations. Why aren't the mac's fans kicking up a notch. Maybe there's a sw hack for fan speed.

Edit: yes there is... smcFanControl

Mon Apr 20, 2015 9:29 pm

sdanaher wrote:Welcome to the world of PC modding eh?

Hmm I had the 980 and ATI 5870 running in the Mac with no problems in the same slot locations. Why aren't the mac's fans kicking up a notch. Maybe there's a sw hack for fan speed.

Edit: yes there is... smcFanControl

I use smcFanControl as well and have a GPU Render preset that raises the PCI fan speed. I'm not sure which cards are installed into which slots in your case, but it could explain the case fan speeding up on its own or not. When the Slot 1 card is powered by the Mac's logic board (as it would with the 5870) the PCI fan speed is determined by the power draw of the card. It draws more power, the fan speeds up. If you bypass those logic board power ports by using an external PSU, or are only rendering with the card that's connected to the external PSU while the Slot 1 card sits idle, the Mac doesn't see that power draw and doesn't raise the fan speed. Hope that explains a little..

Mon Apr 20, 2015 9:33 pm

riggles wrote: I use smcFanControl as well and have a GPU Render preset that raises the PCI fan speed. I'm not sure which cards are installed into which slots in your case, but it could explain the case fan speeding up on its own or not. When the Slot 1 card is powered by the Mac's logic board (as it would with the 5870) the PCI fan speed is determined by the power draw of the card. It draws more power, the fan speeds up. If you bypass those logic board power ports by using an external PSU, or are only rendering with the card that's connected to the external PSU while the Slot 1 card sits idle, the Mac doesn't see that power draw and doesn't raise the fan speed. Hope that explains a little..

that was interesting =) thanks for sharing Riggles!

Mon Apr 20, 2015 9:35 pm

riggles wrote:
sdanaher wrote:Welcome to the world of PC modding eh?

Hmm I had the 980 and ATI 5870 running in the Mac with no problems in the same slot locations. Why aren't the mac's fans kicking up a notch. Maybe there's a sw hack for fan speed.

Edit: yes there is... smcFanControl
I use smcFanControl as well and have a GPU Render preset that raises the PCI fan speed. I'm not sure which cards are installed into which slots in your case, but it could explain the case fan speeding up on its own or not. When the Slot 1 card is powered by the Mac's logic board (as it would with the 5870) the PCI fan speed is determined by the power draw of the card. It draws more power, the fan speeds up. If you bypass those logic board power ports by using an external PSU, or are only rendering with the card that's connected to the external PSU while the Slot 1 card sits idle, the Mac doesn't see that power draw and doesn't raise the fan speed. Hope that explains a little..

That's very helpful yes. The titan is being powered by an external PSU. It has an 8 pin and a 6 pin socket so I assumed I couldn't connect it to the Mac's 2x6pin supplies. Or can i?

Mon Apr 20, 2015 10:26 pm

sdanaher wrote:That's very helpful yes. The titan is being powered by an external PSU. It has an 8 pin and a 6 pin socket so I assumed I couldn't connect it to the Mac's 2x6pin supplies. Or can i?

No, the Mac Pro only has two 6-pin power ports. It can't power the Titan X but it could power the GTX 980.

Mon Apr 20, 2015 10:31 pm

riggles wrote:
sdanaher wrote:That's very helpful yes. The titan is being powered by an external PSU. It has an 8 pin and a 6 pin socket so I assumed I couldn't connect it to the Mac's 2x6pin supplies. Or can i?
No, the Mac Pro only has two 6-pin power ports. It can't power the Titan X but it could power the GTX 980.

It is

So when rendering to the titan the Mac is not sensing the current draw and not spooling up? Could this work: one 6pin Mac power cable on each card and the remaining 6 and 8 pin sockets fed from the external PSU?

Tue Apr 21, 2015 2:04 am

sdanaher wrote:It is

So when rendering to the titan the Mac is not sensing the current draw and not spooling up? Could this work: one 6pin Mac power cable on each card and the remaining 6 and 8 pin sockets fed from the external PSU?

Yes, sort of. I did have some success doing the same thing when I was running 2 Titan Blacks. However, I had a 50% success rate, using two different auxiliary PSUs. One PSU worked, another didn't. My guess is that the first PSU had a rail voltage to the 8-pin different enough from the internal Mac Pro's PSU rail voltage going to the 6-pin, to upset the graphics cards. Crashed hard. I'm not sure on the technicals there, but the next PSU I tried worked in the same configuration.

Tue Apr 21, 2015 8:54 am

riggles wrote:
sdanaher wrote:It is

So when rendering to the titan the Mac is not sensing the current draw and not spooling up? Could this work: one 6pin Mac power cable on each card and the remaining 6 and 8 pin sockets fed from the external PSU?
Yes, sort of. I did have some success doing the same thing when I was running 2 Titan Blacks. However, I had a 50% success rate, using two different auxiliary PSUs. One PSU worked, another didn't. My guess is that the first PSU had a rail voltage to the 8-pin different enough from the internal Mac Pro's PSU rail voltage going to the 6-pin, to upset the graphics cards. Crashed hard. I'm not sure on the technicals there, but the next PSU I tried worked in the same configuration.

As long as I can't actually break the cards or my mac connecting it that way it's worth a go. If not I'll have to either resite the mac (too loud with fans up to speed) or install some extra (but quiet) cooling system.