Leave it off permanently then. You pay maybe 10-15 extra seconds on a cold boot and get a fresh train every time. That's a good trade for not wondering where half your RAM went.
Turn EXPO off and run at plain JEDEC 4800 for two days. If 32GB shows up every single boot at stock, the sticks and slots are fine and what you actually have is failed memory training, where the board gives up and drops a channel instead of retrying.
Then go find a setting called Memory Context Restore, usually buried in the AMD overclocking submenu, and turn it OFF. It caches the training result to speed up boot, and on early B650 boards a bad cached result gets reused on every cold start, which is exactly the on-again-off-again pattern you're describing.
That's a healthy mount. If the noise bothers you, cap the long duration power limit at 180W. You lose maybe 4-6% in renders and drop 10C, and games won't change at all because they never got near that ceiling.
Nothing is wrong. A 13700K under an all-core load will run to its thermal limit and then hold there by dropping clocks, and that limit is 100C. Hitting 95 and parking is the design working, not the cooler failing.
The number that tells you whether your mount is good is not the peak temperature, it's the sustained power. Watch package power in HWiNFO during the render. A good air cooler in a decent case will hold something like 200-230W at 95C. If you're pinned at 95C while only pulling 130W, then yes, something is wrong with the contact.
The idle of 34C already suggests the mount is fine, by the way. A badly seated cooler usually shows up as a high idle too.
GPU, and it isn't close for your use case. At 1440p the graphics card sets your frame rate almost entirely, and one tier up is usually 20-30% more performance. Going from a mid NVMe to a top one changes level load times by a second or two and changes frame rate by roughly zero.
16GB is genuinely enough for gaming and photo editing today. If you find yourself short in two years, a second 16GB stick is a ten minute job and the price will have come down.
Safer, yes. But the failure mode is that the mismatched pair won't run its rated speed, which costs you a couple of percent, not that it won't boot. Weigh a couple of percent against 25% more GPU.