OTOY Forums

cgcris wrote:I've got my egpu working, would it be possible to plug the "Amfeltec 4x to 4 PCIe 1X" and get 4 cards rendering?

Thanks,
cris

If you are on windows, yes. I have 2 titan black and 2 780ti connected on it for use on octane.
if you'on on MAC, I read somewhere on the forum that it won't work (as glimpse said)

Hi,
I just test to add another GPU (580GTX to the setup) but fail ! the 580GTX works but one of the 780ti fail (See GPU-Z) and not displayed on octane.

Hello!

I just wanted to share I had a similar thing happen to me recently with the card suddenly dropping out, showing an unknown Bios in GPU-Z, and no longer being selectable in Octane.

As background I had a Titan X as primary, connected to an internal 1500 W PSU that was also powering the motherboard. Then I had 3 separate Titan Z (6 cores) running off an external 1600 Watt EVGA PSU, connected to Mobo by molex powered PCIE risers using a USB 3.0 cable as conduit. Everything played nice.

I added a 4th Titan Z to the mix and I started running into problems, after messing around and running renders for about 10-20 minutes I would lose GPUs on Octane (GPU failed), and they would show Unknown Bios in GPU-Z...but interestingly they would be gone from GPU-Z, but still listed in device manager and the NVidia control panel.

I began to think one of the cards was failing, because I had a previous Z fail. But then I started noticing that it was different cards of the 4 that were dropping off at different instances. So, either all were failing, or something greater was the issue. What wound up happening was I tried using MSI Afterburner to watch temps, and they were all getting hot, really fast. 2 of my 4 are factory OCd, and they really got hot fast. I then suspected may e they were dropping g out be quad they got too hot, or used too much power.

Anyway, I read up on MSI Afterburner and was able to down lock the 2 OCd cards, and also set the fans to hold temps more proactively, and I didn't see the problem anymore. So MSI Afterburner can help stabilize cards from getting too hot, which means they draw less power. Only thing was that I was going nuts monitoring that the temps weren t going close to 80 C, because then I got kick offs again.

So, next I got a 2nd EVGA 1600 W PSU, and moved 1 card to it. So 3 on one, 1 on the other. And guess what. The temps were by default lower even without fan management on MSI. When they got hot, no drop offs.

In a nutshell, maybe either your cards or PSUs are coming to some power threshold point and are shutting themselves down, or the PSU is doing something. You could try MSI afterburner to force a stable situation, and if said stable situation can be achieved, chances are its a power thing. Maybe adding another PSU to handle one or 2 of the cards in the mix could make it more stable ultimately. But, just trying to offer some suggestions, hope my story gives some help.

Thanks for sharing your experience.
That means you have 9 GPUs and 2 types of cards.
I don't think that a power problem as I have 1600 PSU for titan black an 780ti and 580GTX. and another 1600W on the main system with the 3 other titan.
All are water cooled and get max about 40°C on octanebench.
I think about a lake of IO mem on my BIOS. I have 4 types of cards. I will try to free up some IO by disable some device. Or if I could find one more same type of board ?
I have the same riser USB3. Titan Z is great, but not easy to find a waterblock.

Itou31,

Looking at your problems I think that what Tutor wrote about IO space may be an issue.

Notiusweb,

Yes, to power 4xZ you need 2400W+ of power. Not surprised that 4th Z failed under 1600W. Some more precise calculations of power draw can be found at my log and Glimpse article.

Itou31,

When you are encountering your issue, is it constant, in other words, can the issue be replicated identically (ie same card failing at same time, etc). Or does it work sometimes and not others...In my case, I could always restore recognition and use of all GPUs after a shutdown and boot up, but then once I started rendering, I would get issues. And in my case the card failure wasn't consistently the same. Maybe he consistency, or lack if consistency, could give insight. Ultimately, I want to hear that you have 50 GPUs with no issues!!!!

(Again, in my case I solved at first with MSI Afterburner and then later an additional PSU. ) My four Z's are fan only. I can use my X too, for 9 cores, I just don't bother too because I want a smoother UI experience.

Sometimes I wish if I put a mirror in front if my cards, my system would see 8 Titan Z's, for a total of 16 cores Z...

Notiusweb wrote:Itou31,

When you are encountering your issue, is it constant, in other words, can the issue be replicated identically (ie same card failing at same time, etc). Or does it work sometimes and not others...In my case, I could always restore recognition and use of all GPUs after a shutdown and boot up, but then once I started rendering, I would get issues. And in my case the card failure wasn't consistently the same. Maybe he consistency, or lack if consistency, could give insight. Ultimately, I want to hear that you have 50 GPUs with no issues!!!!

(Again, in my case I solved at first with MSI Afterburner and then later an additional PSU. ) My four Z's are fan only. I can use my X too, for 9 cores, I just don't bother too because I want a smoother UI experience.

Sometimes I wish if I put a mirror in front if my cards, my system would see 8 Titan Z's, for a total of 16 cores Z...

Notiusweb,

could you upload a photo of your computer?

Yes ! I have success adding the 580 GTX to the setup by adding registry key adviced by Tutor, without disableling other devices.

itou31 wrote:Yes ! I have success adding the 580 GTX to the setup by adding registry key adviced by Tutor, without disableling other devices.

Capture.JPG

Do all gpus work under Octane now?

Yes ! and a score of about 775 on octanebench.
They are all stable on windows 8.1 64bits.
Tried on windows 10 but no drivers for 580GTX.

update for power consumption : measured the input power of the whole 2 rig with a power meter :
- at standby (idle windows) : 320W
- at full octanebench : 1788W (up to 2000W peak for 1 or 2 seconds)

As I can disable power on the external rig, I could save about 140W while only surfing on web. I think to only enable all GPU for final render, as my primary rig has already the 3 titan.