Question 64GB DDR5 Fails, 32GB Okay

I think the issue is with my motherboard, an ASUS ROG Z790 Maximus Hero.

Twice now, when I install 4 sticks of RAM, my BIOS won't post. But with just 2 sticks, it does, and works fine.

I've tried upgrading to 64GB of G.Skill Trident Z5 DDR5-7800 (4x16GB sticks) from my original 32GB, but BIOS wont post. Returned the 2nd set, bought 3 months after the original.

Now I've tried 4 sticks of Corsair Dominator Platinum DDR5-7600 C36, 2 sticks post, 4 doesn't.

I've noticed that with just 2 sticks, the default timing is 4000, and then I set the XMP timing in the BIOS.
But with 4 sticks, the default is 3600, and seems to have a conflict of timings between the sticks. They were/are all matching sets!

Is this my motherboard?
Should I go with a Gigabyte Z790 AORUS Master?
Or just ditch the idea of 64Gb (4x16GB)?

I like the cosmetics of the Corsair over the G.Skill. And 7600 v 7800 is not that much.
 
Solution
I think the issue is with my motherboard, an ASUS ROG Z790 Maximus Hero.

Twice now, when I install 4 sticks of RAM, my BIOS won't post. But with just 2 sticks, it does, and works fine.

I've tried upgrading to 64GB of G.Skill Trident Z5 DDR5-7800 (4x16GB sticks) from my original 32GB, but BIOS wont post. Returned the 2nd set, bought 3 months after the original.

Now I've tried 4 sticks of Corsair Dominator Platinum DDR5-7600 C36, 2 sticks post, 4 doesn't.

I've noticed that with just 2 sticks, the default timing is 4000, and then I set the XMP timing in the BIOS.
But with 4 sticks, the default is 3600, and seems to have a conflict of timings between the sticks. They were/are all matching sets!

Is this my motherboard?
Should I go...
I think the issue is with my motherboard, an ASUS ROG Z790 Maximus Hero.

Twice now, when I install 4 sticks of RAM, my BIOS won't post. But with just 2 sticks, it does, and works fine.

I've tried upgrading to 64GB of G.Skill Trident Z5 DDR5-7800 (4x16GB sticks) from my original 32GB, but BIOS wont post. Returned the 2nd set, bought 3 months after the original.

Now I've tried 4 sticks of Corsair Dominator Platinum DDR5-7600 C36, 2 sticks post, 4 doesn't.

I've noticed that with just 2 sticks, the default timing is 4000, and then I set the XMP timing in the BIOS.
But with 4 sticks, the default is 3600, and seems to have a conflict of timings between the sticks. They were/are all matching sets!

Is this my motherboard?
Should I go with a Gigabyte Z790 AORUS Master?
Or just ditch the idea of 64Gb (4x16GB)?

I like the cosmetics of the Corsair over the G.Skill. And 7600 v 7800 is not that much.
If you buying two kits of 32gbs that's your problem..... You. Need to buy a single kit of 4 sticks or 2 sticks.... But buy two separate kits messes with the system doesn't matter if their the same kit or not.... Ram is paired with kits of known cards that work together mixing and matching random sticks not sold together is always a betting game and just like the casino odds stacked against you
 
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Solution
If you buying two kits of 32gbs that's your problem..... You. Need to buy a single kit of 4 sticks or 2 sticks.... But buy two separate kits messes with the system doesn't matter if their the same kit or not.... Ram is paired with kits of known cards that work together mixing and matching random sticks not sold together is always a betting game and just like the casino odds stacked against you
If you buying two kits of 32gbs that's your problem..... You. Need to buy a single kit of 4 sticks or 2 sticks.... But buy two separate kits messes with the system doesn't matter if their the same kit or not.... Ram is paired with kits of known cards that work together mixing and matching random sticks not sold together is always a betting game and just like the casino odds stacked against you
Even from same manufacture, same series, same model #….everything the same? I get it, but it didn’t use to be like that.
 
Even from same manufacture, same series, same model #….everything the same? I get it, but it didn’t use to be like that.
Yes and it wasn't as bad with older dimm because it wasn't being pushed to it's max clock potential to begin with so it leaves a little wiggle room but still was a issue newer dimms are already being pushed to such high clock rates there is no telling what clock rates will be subtle to each stick itself so they still have to make sure what ever timming one stick picks the other will agree with and match
 
04/22/2023 FOLLOW UP:

white.a.drew was right. It's the multiple kits. This is how I know:

I bought a new motherboard to try: Gigabyte Z790 AORUS Master.

This WAS the build:
i9-13900K @ 5.2GHz
GIGABYTE Z790 AUROS MASTER
2 kits of 32GB (2x16GB) Corsair Dominator Platinum DDR5-7600 C36 RAM
Asus TUF GeForce RTX 4070 Ti OC (or Gigabyte AORUS GeForce RTX 4070 Ti Elite)
Samsung 990 Pro 1TB (OS)
Samsung 990 Pro 2TB (Data & Media)
Samsung 860 QVO SSD (Back Ups Sync'd)
Toshiba 6TH HHD (Back Up of Back Ups ALL)
LG Blu-Ray Read & Write LightScribe Player (HL-DT-ST BD-RE BH10LS30)
Corsair H115i RGB PRO XT CPU Cooler
(6) Corsair 140 ML RGB Case Fans, RGB controlled by iCUE Lightning Node, fans by motherboard
Corsair 1200AXi PSU
all in a Corsair Obsidian Series 750D Case
Microsoft Windows 11 Pro x64 (build 22H2)
Dell 3415W via Display Port

I got thru BIOS set up and Windows install without any issues.

THEN, as I was doing hardware driver installs and software installs, every once in a while, I would get the blue screen of death, stating something about Memory errors (it flashed so fast, I couldn't write down the codes), and the system would restart.

After about the 5th error, I gave up!

I tore apart the new system, put back together the old system, and reinstalled everything. NO ISSUES!
I did keep one kit of 32GB (2x16GB) Corsair Dominator Platinum DDR5-7600 C36 RAM, instead of the G.Skill Trident Z5 RGB 32GB (2x16GB) DDR5-7800. I just like the Corsair better than the G.Skill, even if I kept "only" DDR5-7600 vs. DDR5-7800.
(BTW: I can't return one of the Corsair kits, as I bought it off of eBay for $400 from a private seller. The other kit I bought directly from Corsair for $589.00, which I did return and get a full refund. I'm selling the G.Skill kit on eBay starting at $200.00, when I bought it for $425.00 in 12/22.)

No more upgrades to this system, until the next gen of Intel CPU's (Intel 14th gen Meteor Lake) release schedule for Q3 2023 (?).

BUT, I might update the case. I like the Corsair 7000D Airflow Full-Tower ATX in Black, with a Corsair RM1200x Shift Fully Modular ATX PSU.
I like this PSU because the ports are all on the side, the right side of the case, to "hide" wiring. But you need a case with a side cut out at the PSU to accommodate the wiring.