Since you have the lid off habits: check it once a year but don't make a routine of leaning over an open tank. The gas coming off it is genuinely dangerous in confined spaces and people underestimate it every summer. Look, close it, walk away.
Wes
@warranty_wes
Reads the warranty terms before buying and has the replacement parts to show for it.
What would worry me instead: a needle that jumps around while you drive, drops to empty and comes back, or a gauge that reads full with a tank you know is half empty. Those are sender or wiring faults. A slow top and a fast bottom is just geometry.
It happens again whenever you change RAM, change the CPU, clear CMOS, or update the BIOS. Not a fault, just the same job being redone. Worth remembering so you don't panic in six months.
Worth adding, when the truck comes, ask them to open and photograph the distribution box. A tilted or clogged D-box sends everything to one trench and drowns it while the other three sit dry. It's a much cheaper fix than a new field and it looks identical from the lawn.
The reverse happens too. Someone in the next room starts a shower, you lose hot, and you get thirty seconds of cold. Less dangerous, equally rude.
If it survives at JEDEC but still drops a channel, get a bright light and a phone camera on the socket contacts. AM5 is LGA, so the pins are in the board, and one flattened contact in the memory address area will kill exactly half your capacity while everything else works normally. Zoom in on the photo rather than squinting at it.
Timing. Leave it off for 30 minutes and try, then off for eight hours and try. If 30 minutes is always fine and overnight is always broken, that's a cold start supply pattern. If it fails at both, go back to the slot.
Don't rule out the PSU. After eight hours off the bulk capacitors are fully drained and the 12V rail has to ramp from nothing, which is the hardest thing it ever does. If it's been off twenty minutes it starts easier, which matches what you're seeing.
Check that the cooler's fans and your case exhaust are pointed the same way. I've now seen three builds where the tower cooler was rotated 90 degrees so it blew into the side panel. Everything looks tidy, temps are terrible under load and fine at idle.
A few drops of valve grinding paste or even a pinch of fine sand in the recess gives the bit something to bite. Sounds like nonsense, adds a genuinely noticeable amount of friction. Cheap enough to keep a tube around.