Sorry it took so long for me to get back to you, I would attempt removing all the memory, turn on the computer and wait for it to start beeping with it’s error code then proceed to power the machine off. Then I would try installing only one stick in slot one and then boot the computer, let it sit for at least one minute if you have a black screen. I have see computers take a minute to determine the memory, then they will turn off and back on. If you are successful windows will boot.
If windows does not boot then you will need to attempt resetting your BIOS, check the motherboard manual for steps on how to do so.
If windows did boot then go ahead and shut down the computer and install the remaining stick in slot 3. For dual channel memory to work properly you will have to stagger the slots you use.
In super rare cases I have been forced to use slots 2 and 4.
Hope all goes well.