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Hello

Has anybody built a 3x/4x Titan RTX system?

I am running an ASUS x299 sage motherboard that can support 4x GPUs in x16 PCI-e speeds.

I am looking to install 3x Titan RTX cards in the system.

good day, nisachar,

new turing cards like 2080ti and TitanRTX are pretty thirsty and also rather toasty as an effect. That's the reason why NVIDIA redesigned their cooler and went from blower type they had before to new one, just to be able to remove all the heat effectively.

the fact that gaming cards do not have dual slot NVLINK only triple and quad also points to the fact that You should not use those cards at every second PCIe slot (1, 3, 5, 7 on Your mentioned 7 PCIe slot motherboard). Thus logically, if You plan to have four cards (two NVLINKed pairs) I would go with some server mobo with 11 slots seating cards with extra slots between (1, 4, 7, 10) so between all of those You would have and extra gap for cooler to breath.

why is cooling that important? as mentioned before, new cards are pretty toasty and they need optimal airflow to remove that heat. To give You a bit of perspective, 2080ti is about 10C warmer than the warmest 1080ti on the same watercooled loop (and that's actually why blower cooler equipped 2080tis are louder in aircooled builds). If You fail removing the heat, You will end up with card throttling down and loosing render speed (quad 2080tis perform anywhere between 800-1200 in OB and while RTX Titan is slightly faster, technically it's more or less the same GPU under the hood, but we do not have too much data on quad T RTX build due to high price tag making build lass popular), not to mention that running daily loads heating up and down would effect life span of GPU in a negative way if You have bad cooling.

There are few solutions in Your case:

* get bigger motherboard if You plan to get 4X cards (what is logical if You care about NVLINK pairing),
* get better coolers - could be some hybrids or simple closed loop options
* build a custom loop (this one is pricey and complex)
* stick with two cards (or three if NVLINK is not a priority)

* last but not least, You can use four cards, just keep in mind that You might end up loosing performance, running cards much more hot than needed and have more noise than needed. system stability during long runs might get compromised as well.

Oh man

Thanks. Been a while since I wandered these parts.

I went 3x cards for now ( slot 1, 4, 7) with a gap in between because of heating issues ( just to test I had put the two 2080tis with no space between them for a while and they would heat up rather fast). Now my case is huge with many fans pulling air in and exhausting, so airflow isn't an issue.

I will be using two cards for rendering while keeping the 3rd one for display.

I just noticed that link is supported since version 2018.1 but I don't see any option to enable it ( I am using a studio subscription of Octane)

For 3 or 4 turing core GPU, it will be good to choose "2080ti Turbo" type video cards, which is one fan configuration similar to typical 1080ti, and designed for compact layout to avoid the need of gaps between the video cards,
Asus and Giga have their "turbo" version for 2080ti.

Yes. I wish now I hadn’t listened to my vendor. Should have gone with the turbo versions instead of the normal ones.

nisachar wrote:Yes. I wish now I hadn’t listened to my vendor. Should have gone with the turbo versions instead of the normal ones.

You can always add custom cooling and even watercool those cards to get the most out of Your build.

We are running 4 RTX Titans on the the x299 Sage motherboard with no problem. We used a huge case and separated the 4 cards using two riser cables, 2 cards attached directly to board. The hottest card right by the processor when rendering 24x7 is 72C on air. The board can work very well for 4 cards they just need to be separated if you plan to keep them on air which I would recommend as the RTX stock coolers work great. 1287 Octane bench with the 4 RTX's.

Thanks, Tom and anifex3D for your replies.

I managed to fit in 3 Titan RTX cards, nvlinked two of them and kept the third one as a pure display/OpenGL card.

Does octane 2019 rc1 support nvlink and RTX on RTX cards? I can't seem to find any settings in the preferences.

@anifex3D : which Riser cables would you recommend?

Thermaltake TT Premium PCI-E x16 3.0 Black Extender Riser Cable. They come in different lengths. These are great cables. There is no loss in performance using the cable vs plugging the cards directly into the board.

anifex3D wrote:Thermaltake TT Premium PCI-E x16 3.0 Black Extender Riser Cable. They come in different lengths. These are great cables. There is no loss in performance using the cable vs plugging the cards directly into the board.

Great. I will get it for my main display card since that is the only one that doesn't require Nvlink in my current setup.