Asrock Z490 Taichi - H150i Block Not Contacting IHS

Parts

Asrock Z490 Taichi

Intel i9-10900K

Corsair H150i Pro RGB

Using

LGA115x/1366 standoffs

Supplied bracket

Problem

Screwing standoffs into bracket leaves several millimeters of play. Mounting waterblock and tightening thumbscrews to standoffs results in no contact between IHS and H150i cold plate. When removed, almost no thermal paste had transferred.

Where is the gap coming from and how is the slack removed?

Update 1: Used 8 washers to space backplate bracket flush with motherboard PCB. Tightened down thumbscrews again - still no contact between IHS and cold plate.

The Corsair website shows the H150i Pro RGB supports LGA1200. Manual doesn't show a different set of standoffs. Is there some updated box that has LGA1200 hardware that isn't reflected in the manual?

https://www.corsair.com/us/en/Categories/Products/Liquid-Cooling/Hydro-Series%E2%84%A2-PRO-RGB-Liquid-CPU-Coolers/p/CW-9060031-WW#tab-downloads

Update 2: I think there is something wrong with the standoffs. The LGA2011-3 standoffs that came with the cooler worked on my Asrock X99 Extreme 4. But the LGA115x/1366 standoffs are either wrong or just plain too long.

Final update, if anyone comes across this.

The part where I eat Crow

Had the wrong standoffs. I feel dumb as for that. I'm sorry.

There part where the cooler needs help

Hardware kit needs to come with nylon washers. Even with the right standoffs the cooler wouldn't make contact with the IHS. I had to space the back plate using washers to get the insert flush with the motherboard PCB in order to mount it properly. It really makes me wish the Intel consumer boards had a mounting system similar to HEDT where there is no backplate, just threaded inserts for standoffs. It means there is no guesswork with PCB width - it all just works.

It really makes me wish the Intel consumer boards had a mounting system similar to HEDT where there is no backplate, just threaded inserts for standoffs. It means there is no guesswork with PCB width - it all just works.

Yeah, no kidding. I don't know how much they save per board by not having a pre-attached backplate, but it can't be worth the endless of amount of end user missteps created from messing around with these brackets. After X99, I was more than annoyed with all my very expensive custom CPU blocks for Z370 that wobbled all over and some where down to the very last thread for security. A standard pre-installed backplate would do a lot of good for a lot of people.