Was PCIe 4.0 on Z490 always planned?
I don't recall PCIe 4.0 ever being in the mix for Comet. But when Comet Lake-S was announced as being a Q4 2019 product, Rocket Lake was still a mysterious force in the distant future, and frankly Intel hadn't provided us with much information about connectivity on any of their future platforms.
Anyway Rocket Lake brings some much needed platform features - dedicated x4 PCIe for NVMe and x8 DMI link to chipset, but I would hope that those aren't too difficult to get right once PCIe 4.0 support has been laid out.
Those are the kind of features that Intel is supposed to do better than anyone else.
However, until I see Intel becoming a lot more talkative about their future plans I will always expect delays for high volumes, no matter the node.
Intel's 2020 and 2021 server picture may have a big effect on how Rocket plays out (especially launch delays and volume).
Right now, Intel is still limping along on Cascade Lake in the server room. Cooper is extremely limited and Ice Lake-SP is MIA. Nearly anything Intel sells is Cascade Lake. And they are still selling it - for now. It's really questionable as to how long anyone will continue buying Cascade Lake for any reason, but hey give Intel credit for leveraging all their sales talent to keep the gravy train running.
Cascade Lake is eating a lot of 14nm capacity.
IF Ice Lake-SP FINALLY launches in some non-zero volume and then Intel miraculously hits with Sapphire Rapids in 2021 at a good clip, depending on how Intel massages the market (namely: can they convince server hardware customers of various stripes to hold off on Milan long enough to give Sapphire Rapids a chance in Q3 2021 and ignore Genoa coming uh whenever?), their demand for 14nm wafers may crater just from buyers holding off for Sapphire Rapids. Which means that lingering Comet Lake products and newly-launched Rocket Lake products will have many more wafers to play with throughout all of 2021.
And that all assumes Intel will have enough 10nm wafers available to serve their customers with Sapphire Rapids, which is another unknown. But I digress.
One of the problems with the Comet Lake-S launch is that several SKUs are plagued by shortages, and Cascade Lake is at least partially-responsible for that. Take 14nm server CPUs out of the picture and that problem vanishes for Rocket. At that point it's a matter of whether Intel has pulled together the design quickly enough to successfully launch in Q1 2021. As I stated above, Intel has historically been really good on platform (crap like the i820 notwithstanding). I personally do not see PCIe 4.0 and x8 DMI being a primary driver in Rocket Lake-S delays. I see the backport effort itself as being the likely culprit (if there is any). Can Intel hit the clockspeed and power targets they want using a modified Sunny/Willow Cove core backported to 14nm? We already know they're having to retreat on core count. Or at least we reasonably suspect, and all early indicators point in that direction. And even if Rocket does perform basically as planned (5.0 GHz turbo limits, +2x% IPC gains), can Intel pull together enough wafers to sell a meaningful number to anyone? Or are they just gonna have to keep shlepping Cascade Lake at deeper and deeper discounts due to delayed Sapphire Rapids and delayed/failed Ice Lake-SP? If Intel's 10nm server products don't show up in sufficient volume to take pressure off the 14nm fabs, the only way Intel will be able to sell lots of Rocket dice is if customers abandon Intel's server lineup entirely (Intel will fight like hell to prevent that, even if it means pushing more Cascade Lake throughout 2021).
Delay was I believe because they delayed production to open up room for more Cascade Lake XCC.
See above, but if Rocket also has to compete for wafers with Cascade Lake then it could be the same rodeo.