I understand that your system is not able to wake up from sleep and you get a keyboard related post code.
In regards to the problem that you are experiencing, the sleep needs to be supported and working on every device on the motherboard in order to work properly.
For this I mean that, a SATA or USB device, the video card, the power supply, the motherboard and the processor need to work properly together to accurately enter sleep mode and wake up from it.
I recommend you to try swapping parts to check which one is the culprit on this behavior, you have already discarded the keyboard as being the cause of this behavior.
Thanks, that is probably good advice but a tall order. Would it help if I told you that I was reading the status code upside down and it was actually E6 not 93 but I have no idea whether that code can help tell us where we got stuck?