Why don't you test your RAM modules by installing one at a time and see if they work properly. If so, then install both again. Or, download and run
EVEREST Free Edition 2.20. It will tell you what memory is installed in what slots. This should confirm whether both memory modules are being recognized or not.
Regarding processor speed, access your BIOS and see whether it has settings for CPU frequency. I have a computer with an ECS motherboard where I had the same problem as you. I learned that a BIOS setting sometimes changed, without me changing it. I replaced the power supply in that computer, for other reasons, and that problem has not occurred again. However, recurring loss of BIOS settings could be a sign of a weak CMOS battery on the motherboard. Those batteries can be replaced.