What will happen if I remove the RAM while the computer is on?

Solution 1:

Nothing good.

You're likely to fry the memory chips as well as the motherboard.

If the system isn't hot-swappable, there's likely some electric interaction between the RAM and the motherboard. Removing the RAM while the current is flowing will be very likely to create sparks and strong currents that will wreak havoc on your system.

If you're lucky enough not to cause any physical damage, the system will likely hang. During power-up the BIOS determines how much physical memory is available and sets up the system to use the resources accordingly. The memory is likely to be allocated to some piece of software, either BIOS, OS or some user software. When you remove its memory, that software will lose some of its code or data, which is not healthy either.

Solution 2:

I just did it thinking it was off, it sparked and now nothing. It will not boot up, I changed the RAM and still nothing it sounds like it booting up but the monitor does not detect the PC.

Solution 3:

I happen to be in the process of selling a bunch of memory modules and setup a Memtest station consisting of two desktop PC's, but only sharing one monitor (I was just unplugging the VGA cable and switching it to the other desktop to see the display on the other PC). I was running Memtest86+ on one PC to test DDR2 memory, and the other was testing DDR3. So I had 3 sticks of DDR2 memory that sucessfully passed the memtest, but the test continued on for 8 hours. I thought I powered off the PC since the monitor was off, but I merely unplugged only the monitor. I forgot to pull the power cord as well. So I just started popping out each stick one by one. When I took out the last stick of RAM, I realized the PC was actually powered on the whole time. I looked up what would happen by pulling ram on a powered on PC and came across this thread.

Well I put all three DDR2 memory modules back in the motherboard and re-ran memtest86 on them. All 3 sticks passed and I let it run for 3 hours total. Not a single error came up. Good!