Power save mode always activated

My Desktop having ASUS Mother Board and a dual- core processor, Two years old.
Monitor Dell One year old.

My SMPS atx 350 watt, worked for 2 yrs. but burst out due to clogging of its vents.
I replaced the same with 400 Watts yesterday and worked for 24 hours.
Today it started going into POWER SAVE MODE and I could not sort out the problem

I waited for about 5-8 mts. to see if the monitor riverts to normal, I saw a display
appeared showing POWER SUPPLY SURGES DETECTED DURING THE PREVIOUS POWER ON.
ASUS ANTISURGE WAS TRIGGERED TO PROTECT SYSTEM FROM UNSTABLE POWER SUPPLY UNIT.

I went to BIOS > POWER. There are various voltage levels shown there in blue letters for normal operation. I had one in red letters - showing 2.5 V where normal is 3.3 V.

I think the culprit is the atx power supply unit. This unit is new and unused for more than a year and hence cannot claim warranty. Before I invest for another atx power supply can anyone advise if the SMPS is faulty or to try any other option or possibility of faulty hardware/software.

Regards,