Question 3 beeps on boot, happened before and fixed this time no

Mar 6, 2023

I have a 2008 desktop Intel DP35DP motherboard Quad core 2.4 with Nvidia Geforce 9800gt
in the past it made the 3 beeps because the ram was different and not compatible
a month and a half ago I increased the ram to 8gb, 3 Micron 2gb slots and 1 Kingston 2 gb slot
suddenly 3 days ago the pc makes the 3 beeps at startup no matter which ram I put in any slot, old or new one
the last time it started was 4 days ago when the first time it made the beeps while on the second boot it started normally
In the past the same thing had already happened to me and I solved it by removing the CMOS battery and resetting the jumper by putting it on pins 2-3 but this time it doesn't work
I also cleaned the pc, updated bios, tried to have the monitor on while connected to GPU (in some cases it makes the beeps a little later than usual)

I know it's old but for me it could still work, maybe it's something to do with the GPU apart from the ram