@jonny quick
No,just power failure and internal battery dead,after restart time was set to 2002
This doesn't sound right. It takes at least 5 years for the "internal battery" (aka CMOS/BIOS battery) to die. Unless you have a very old Server using more recent software (doubtful).
If the battery DID die, there's a problem. CMOS battery issues cause all manner of flaky problems, and they are sometimes intermittant (the worst). More likely you have a motherboard problem, if this battery really did die.
Did it get replaced?
Who changed all the BIOS settings back to the way they were, and did that person know what they are doing? Those settings can get very "exotic", and unless either the person knows that particular machine very well, or has general knowledge and is willing to research each option they are not familiar with, it is entirely possible that some oddball setting in there is different than it used to be, which is why your performance is different.
The first thing to do is rule-out if you have a hardware problem. Also, power outages can sometimes be VERY catastrophic. You should think of the power surge of the power coming back on as being the equivalent of a lightening strike. A good-quality Power Supply is an absolute essential, and a poor quality PSU could easily fail due to power irregularities and be the cause of your problems.
Do you know the specs of your PSU (manufacturer, model number, rated power output) ? Or the specs of the whole system, if it is premanufactured (not custom-built, like a Dell, HP, etc...)