With horrible pc parts price I bought this Office PC with a Asus Prime B360M-K to upgrade as a gaming pc but the chiniese GTX 1650 Low profile I bought does not boot sometimes. It gives 1 long beep and 3 short beeps gap and another beep. card fan does spin all the time.
low psu, or might be something sleep/uefi/fastboot related
Give us a close up of your motherboard here.
Also, try booting without the optical drive plugged into anything. It’s useless anyway and it might be just enough of a difference in power to get you booted reliably. If that does work though, I wouldn’t be surprised if you see crashes when you throw a graphics workload at your card and it tries to draw its full power.
unplug the optical drive makes it boot properly it seems to be a psu problem will upgrading to 500W work? or I need 600W?
Do you still use the optical drive? If not just leave that unplugged
The GPU (and CPU, for that matter) at full load will draw more than it does at boot. Just because disconnecting the optical drive bought enough headroom to successfully boot does not necessarily mean that the computer will be stable under load.
500W is plenty, just make sure it’s from a reputable brand instead of the no-name that came with the case.