Unless you're running a lot of memory (think more than 64gb) you won't have any trouble below DDR5-6000, most Intel CPUs run up to DDR5-7000 just fine.
Make sure you're running the latest BIOS version, they do improve compatibility and stability for fast memory from time to time.
If the need is gaming, anything above an i5 is icing on the cake. Yes, it's a little faster. But not noticeably so.
Anything from a 120mm tower cooler will give you most of the performance. Aio-coolers are probably your best choice if you want the reasonable maximum.
6 GHz all core is possible, but needs lots of voltage and very good custom cooling on a 14900K. Nothing that you would normally be able to do, and definitely not all chips either.
Intel is imploding at the same rate as AMD is developing their consumer GPU raytracing capabilities. Very slowly, possibly not at all.
They have issues, their CPUs are outmatched in some areas by AMD and others. But Intel is not dead, they're probably not even dying.
Instinct MI300(X) is THE hot shit to get for everyone who can't get H100/GH100 because they're in short supply.
AMD is a larger player than people realize, especially with AI frameworks supporting ROCm now. Nvidia got a head start, but Intel, AMD and a myriad of Arm/RiscV custom-chip-companies are not asleep.
Can they? Yes!
Will they? Probably not. Nvidia has more software developers, more industry support, an already established technology, more money... I don't see it coming.
7200 on a prime board with 4 slots is pure luck. In your case, you didn't have any. I wouldn't blame the cpu before you've tried it on a proper motherboard.
Or just run 6800 or something, the difference isn't huge.
i7-4790k is the highest drop-in replacement for the board after you do a bios update first.
That being said, it's a pure waste of money. Don't do it.
Also, to answer the question from the title: The highest Intel CPU that can pair with a GTX 660 Ti is the Intel Xeon Platinum 8480+. And on the mainstream-desktop it would be the Intel Core i9-14900K.