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Question about Decklink 8K Pro

PostPosted: Fri Jun 21, 2019 5:07 am
by Sandman
There seems to be a 6-pin power connector on the back, but I can't find any documentation explaining if it always requires that to be plugged in. The tech specs page says the card draws 19 watts, which is well within the spec to be powered by the PCIe slot alone. Is there a certain threshold of bandwidth (for example, three inputs receiving 4K60, or all four) or other situation in which the power connector is required?

I'm curious because I'm running a mobile recording/streaming rig using a Thunderbolt 3 enclosure (currently a Sonnet Echo Express SE-I, but will be upgrading to an SE-III, neither of which have internal power connectors) and a Decklink Duo 2. If I'm able to use the 8K Pro with a couple of 4K30 inputs (and possibly one or two 1080p60 outputs) without needing the power connector, I'll upgrade to that, but if not, I'll just get a second Decklink Duo 2 when I upgrade my TB3 enclosure

Re: Question about Decklink 8K Pro

PostPosted: Wed Jun 26, 2019 1:32 am
by Dave Del Vecchio
It's a little unclear why the 6-pin auxiliary power connector is needed if the DeckLink 8K Pro card draws less than 25W, but I think you can probably get by without it.

I have used the DeckLink 4K Extreme 12G card without the 6-pin aux power connector without any problems in both regular motherboards and PCIe expansion enclosures (that card draws up to 30W, so the secondary power connector makes some sense there).

Keep in mind that the DeckLink 8K Pro requires a PCIe 3.0 slot though, so I'm not sure it will work with the Sonnet Echo Express SE-I (which only has a PCIe 2.0 slot). I think it should work with the Echo Express SE-III though. That enclosure has a 120W power supply, so it should be enough for the 8K Pro card, provided that you don't have a bunch of other power hungry cards installed in the same enclosure.

Re: Question about Decklink 8K Pro

PostPosted: Tue Feb 11, 2020 7:19 pm
by ashraj
The Decklink 8K Pro consumes 19 watts, but Sonnet's Echo Express SE I (Thunderbolt 3 Edition) can only provide 15 watts through its PCIe bus. Indeed, Sonnet says that the Decklink 8K Pro will work with the Echo Express SE III and IIIe. (I would cite all of these specs, but I am not allowed to post URLs yet.)

Re: Question about Decklink 8K Pro

PostPosted: Tue Mar 24, 2020 9:05 pm
by Michael Tiemann
I am just now sorting out my own issues with the Decklink 8K card and a Sonnet Echo-Express III expansion box. My principal computer is an iMac Pro with Vega 64 graphics. What I'm finding is that the PCIe x4 slot (and the additional, real-world limitations of TB3's interface with PCIe x4) limit the card when trying to use 60p. Resolve will play 2160p60 videos back to my Mac's monitor screen at full speed no problem, but when I try to play them through the decklink card, performance is throttled to 37 fps. Also, I cannot use 4:4:4 mode.

If/when I get a real computer which has a PCIe bus I can plug the card into, I can test whether the speed limit is really Resolve's fault, the card's fault, or the expansion box's fault. But I strongly suspect that the bottleneck is between the computer and the card and either because of TB3 limitations or PCI x4 limitations, or both.

Re: Question about Decklink 8K Pro

PostPosted: Tue Mar 24, 2020 9:22 pm
by Andrew Kolakowski
Decklink 8K Pro needs x8 gen3 slot to be able to operate at every supported mode.
UHD 60p should work over TB3 though, including 4:4:4 (requires around 2GB/sec).

What format are you playing back? Are you not hitting CPU limits?

UHD 4:2:2 at 37fps is <1Gbyte/sec, so this should not be TB3 issue ( I assume you have no other devices, like GPU in this case). TB3 real bandwidth is probably around 3GB/sec out of its 4GB/sec theoretical.