Blackmagic Forum

Hello all!
so we have been testing the Decklink 8K pro on a setup for a live event and we seem to have a strange limitation with the output of the card.
Our setup includes 3 x 4K projectors, each has 12G SDI connection, when we connect the projectors to the BM Decklink 8K, and set the output from resolume to 2160P50, we are getting the signal out to the first two projectors, but the third one isn't receiving any signal, when we put this down to 2160P30 the three works fine, any idea why is this happening?

Our setup includes:
MotherboarD: ASUS PRIME Z690-P
GPU: NVIDIA RTX3060Ti 8GB

can anyone advise if this is a hardware issue or software?

Sounds like a PCIe bandwidth issue. Your motherboard supports only 1 x16-slot, the rest are all x4.


2160p50 = 12Gb/s per signal
2160p30 = 6Gb/s per signal
PCIe 3.0 lane speed = 8Gb/s
PCIe 3.0 x4 = 32Gb/s max transfer speed to the card.
3x 12Gb/s = 36Gb/s !!

If you don't need full transfer speed to your GPU, you can try placing the Decklink card in the guaranteed x16-slot. Otherwise you need a different CPU architecture that supports more lanes.

Does the issue follow the output or the destination?

I’d check the firmware and or cabling on the rogue PJ first.

Good Luck

Asgeir Hustad wrote:Sounds like a PCIe bandwidth issue. Your motherboard supports only 1 x16-slot, the rest are all x4.

z690.PNG

2160p50 = 12Gb/s per signal
2160p30 = 6Gb/s per signal
PCIe 3.0 lane speed = 8Gb/s
PCIe 3.0 x4 = 32Gb/s max transfer speed to the card.
3x 12Gb/s = 36Gb/s !!

If you don't need full transfer speed to your GPU, you can try placing the Decklink card in the guaranteed x16-slot. Otherwise you need a different CPU architecture that supports more lanes.

I believe you are right, will try to swap the GPU with the DL, I read online that the 3080TI can run on a 3.0 PCI with no significant drop, but I am curious to understand your analysis, you said:

2016p50 = 12Gp/s per signal, so I will need 36Gp/s to manage the signal I have, but how come I am getting the 3 outputs on 2160p30 on PCIe 3.0? since the three outputs are a total of 24Gb/s and the current PCIe used is 3.0 with lane speed of 8Gp/s?

Hasanhina wrote:[...]
I am curious to understand your analysis, you said:

2016p50 = 12Gp/s per signal, so I will need 36Gp/s to manage the signal I have, but how come I am getting the 3 outputs on 2160p30 on PCIe 3.0? since the three outputs are a total of 24Gb/s and the current PCIe used is 3.0 with lane speed of 8Gp/s?

2160p30 = 6Gb/s, that's why that works, total of 18Gb/s.

I switched the BlackMagic card to the PCIe 5.0 slot but the problem is still the same, I am getting two 2160p50 on two projectors and the third one isn't getting signal, once I bring down BM card configuration to 2160p30 they all receive the signal fine, not sure what is the cause of this issue but it is very frustrating that I can't get more than 2 outputs in a card that is supposed to do 4

Hello again!
I tried to swap the car and placed the BM card on the x16 slot PCI4 5.0 but the problem remained the same, I am not sure why the card isn't using the full bandwidth of the slot in this case?

Hello so I found this on the support page for deck link:

The following motherboards are recommended for use with DeckLink 8K Pro:

Gigabyte X99-UD4-CF
Gigabyte X299 UD4
Gigabyte X399 AORUS Gaming 7
Gigabyte Z97X-UD7 TH
Supermicro C7X99-OCE-F

If we switch our ASUS PRIME Z690-P to one of those motherboards, will we be able to output 4 2160p50 from the DL card? although the PRIME z690-P has one Intel® 12th Gen Processors* 1 x PCIe 5.0/4.0/3.0 x16 slot which I am using for the DL card, but still we can't get more than 2 outputs of 2160p50 from the DL card, is if this was a bandwidth issue why can't we get the necessary output of 4x2160p50 which would be 12x4=48Gb/sec from the PCIe 5.0 x16?

here is out full built for feedback on what the issue might be: