Help with Sleeper computer

[Samer3pts]

I just build a sleeper computer using a Dell Optiplex 790. I started the computer and was able to boot into the bios. In the bios I did change the ram frequency but did not change anything else. I saved and turned off the computer. I plugged in a flash drive with the intention of booting back to the bios then telling it to boot to said flash drive to start windows as normal. So I turn it on for the second time but the bios is not coming up. It seems as if the keyboard isn’t getting a signal from the computer because caps lock lights aren’t turning on and off like they did the previous boot. I’m not sure what else could be the issue. It is still recognizing the display. The only other thing I could think of was potentially accidentally doing something in the bios to mess something up but I don’t know for sure. So my question is what happened between the two boots and what could I do to fix any potential problem stopping me from getting into the bios. 

[Harmsway1283]

If the frequency isn’t stable on start up then you won’t be able to get to the BIOS without clearing the CMOS battery to reset the BIOS.

 

 If the POST process doesn’t get past validation of the DRAM, then PCI initialization won’t happen and your USB ports won’t work as advertised.