What is DeckLink for?

OK, so I have zero need or want to capture video. Everything I'm getting is already a file via hard-drives.
What I am looking for is SDI or 10 bit HDMI output to a monitor. Which, I can get cheaper than the DeckLink extreme if I don't need capture options( and I really don't HAVE to have that at this point either)...however, does the card accelerate the video playback on the computer?

Does it make 2k, 4k play back on the system real-time? Or is it just an in and output card that handles a lot of data in and out? To me, having GPU acceleration, high-end 2 nvidia cards and fast hard drives , raided SSDs and a NAS card, is what I thought I needed to get 2k or 4k to play back in Resolve or Premiere . But do I need this as well? How would this benefit me , who again, needs zero video capture or output? Thanks for any sage like advice here.

Any of the approved BMD cards will get you secondary output. I don't know about the Intensity Pro as I've never used one and there's no mention of 10bit, but I have heard they work fine with Resolve. But for 10bit HD SDI you really have only 2 options afaik - Extreme 3D or 4K Extreme.

So, will it offer any playback acceleration when using Resolve? Or is that all the computer throughput, motherboard, SSDs, GPU? The hardware guide is kinda strange, you can build a machine that is, generally, as fast...or faster than that HP build they recommend for half the cost, but they say thats one of the only ways to get reliable 2k or 4k playback? . So, was curious what a Decklink 4k would do for me minus in and out.

Right now, my Motherboard supports 4 PCI 3.0, dual x16, or 4 at x8.
I have 4 raided SSD drives... getting another 670 card, so I'll have 2, throughput is very high, editing in Premiere and After Effects is very fast, its pretty much getting real time 1080 correction with R Lite without the 2nd GPU ...so was curious if the decklink 4k would help me do 2k or higher playback? If its just in and out, then that can wait for now. Really would like to be able to work with RAW when I get my BMC, but don't want to break the bank.

Depends on your Raid read write speed.

I have an Atto and my Raid read write speeds aprox +- 800 Mb/s. Makes a big difference.
BMD publish striping details you can read I think for various formats.
Radman.

that's fast! I might need to upgrade my SSDs, I'm geting around 550mb read, but dismal right speed, half that.
Does anyone know what the average mb per second 2k or 4k raw is? Guess I should look that up.
EDIT
looks like 2.5 k raw is around 450mb per second based on a couple sites I saw.

[Peter Chamberlain]

The Decklink HD Extreme 3D is used for I/O including providing the signal for your calibrated monitor. All image processing is performed by GPUs and codec processing by CPU. Debayer of camera raw is via GPU except for Red r3d which is via a Red Rocket or CPU.
Peter

That makes total sense. Thanks, I appreciate the response.