BIOS not retaining settings after CMOS battery rep

I?™ve been having problems with my z490 phantom gaming itx/tb3 board?™s CMOS battery.

This is different from a regular ATX CMOS battery in that it is physically smaller in diameter and is attached to a two pin female socket next to the CMOS reset button via a male twin wire connector. In this it?™s very similar to laptop and thin form factor board CMOS batteries. I've not seen them on previous ITX builds, but this is my first Asrock board.

I bought the board second hand a month or so ago. Generally it?™s working well and when I?™ve stress tested it on Windows and Linux it?™s run cool and stable.

BIOS/UEFI settings are retained so long as the PSU is connected to mains power and switched on. It?™s otherwise behaving exactly as I?™ve experienced with other mobos when the battery needs replacing but on a regular ATX board it?™s super simple to swap in a new battery. Whereas this involves taking the IO shield casing and heatsinks apart to access the two pin battery connector.

Initially I bought a pack of five CR2032 batteries with 2 pin wired connectors online and when none of them worked I sent them back, assuming they were faulty because they were extremely cheap.

Since then I've bought several others from more ?œrespectable??suppliers which cost five times as much, but they didn't work either. Over the last three weeks of trial and error I've tried 8 different batteries - though in theory they've been identical in terms of spec: RTS CR2032w twin wired.

I?™m 95% sure I have the correct battery with the correct connector. That said all of the ones I?™ve bought list compatibility with various laptop brands rather than with Asrock specifically - but I think theyre probably pretty generic 3V CR2032 batteries, unless someone here knows differently?

I know that some two pin connectors have a different shape, and that there are also three wire variants - but the one?™s I?™ve had fit perfectly into the header/socket on the board with the male connector from the battery clicking into place on the socket on the motherboard.

Worst case is I?™ll have to live with resetting the UEFI BIOS every time it?™s disconnected from mains power - but I?™d like to figure this out and understand what might be going wrong if possible?

I've inspected the board very carefully visually and for what its worth I can't see any problems like missing components or swollen caps - which I wouldn't expect to see because - as I said - once booted up the board works flawlessly.

I?™m assuming now that probably all these batteries have been good and there?™s something wrong with how the battery supplies current to the BIOS chip when the PSU is powered off or with the circuitry that switches in battery power in the absence of mains power.

Could it be BIOS settings/version related? When I got the board it had a 1.40A (Beta) BIOS installed and I flashed it to v1.60 directly when maybe I should have upgraded the board to the 1.40 non Beta BIOS first?? No idea if this could even make a difference?

I'd also like some reassurance that Asrock doesn't use some specific RTS/KTS CR2032 cell with twin wires I have to order specially?

Anyone any ideas? Heard of something like this before? Anything else to try or test?

Hello. Did you manage to resolve your problem. I have the same problem.