I am using Cooler master MWE GOLD 850 V2 Power supply. Model: MPE-8501-AFAAG-IN. It got damaged because of voltage fluctuation recently and I got it replaced. I am planning to get a voltage stabilizer to avoid further issues. The total power requirement of my PC is only around 450 watts as calculated from coolermaster website. Is it ok that i use a voltage stabilizer of 600 watts capacity?
You're going to need a UPS more than anything, since a stabilizer might stabilize the power to a certain degree before it cuts out and then your system is left unpowered. If you're looking at an UPS, look for a 1kVA UPS.
Just for the sake of relevance, you might want to run us by your entire system's specs for us to gauge your potential power draw.
Your bottleneck here is the device that has the lower wattage, which is the voltage stabilizer. In terms of the number of watts, its ok to use a 600W voltage stabilizer. However, your actual wattage draw shouldn't exceed 600W or more otherwise your voltage stabilizer will overload. If you plan to upgrade your system in the future, you will need to increase the wattage of your voltage stabilizer.
Likewise if your Voltage stabilizer has a higher wattage than your PSU (lets say 1000W Voltage stabilizer vs. 850W PSU) and your overall wattage consumption for your PC nears or reaches 850W, you would need to upgrade your PSU to a higher wattage.
As per the above suggestion, I would also second the recommendation to use a UPS. Most modern UPS have a voltage stabilizer built into them btw and have the added benefit of allowing you to save your data properly before turning off the PC in the case of a power outage.
Keep in mind if you're going to buy a UPS of the 60% VA Rating guideline. You will see UPS with "VA" ratings on them, marketing won't teach you what they really mean.
The wattage of the load has to be less than 60% of the VA rating of the UPS or in other words, buy a UPS with a VA RATING that is at least 1.6x your current or planned wattage load
UPS: 1000 VA, Equipment Load: 900 W, rating 900 VA
The 900W load cannot be supported since:
900 W (Load) > 1000 VA x 60% of UPS ~ 600 VA