I suggest that you do a web search for "power supply calculators", choose one and feed in all of your system's hardware. You didn't indicate what peripherals or graphics solution you were using, so I did a quick calculation using a reasonably-loaded system design. Even then, requirements came in well under what your supply provides. What does this mean? Either you have a failing power supply or, more likely, something else is responsible for this. Please provide a better explanation of your system, what you are seeing happen and what you do about it to get going again.
thanks for reply i will explain you in brief
from past 6 month i assamble my pc..i am graphic designer/3d artist so i need good system for work..i purchase
i5 3450 lga 1155 model..
gigabyte b75d3h model motherboared
4 gb corsaire ram
Wester didgital 500 gb HDD
and SMPS its iball company...
and i had geforce gt520 GPU (but now its broken)
now the main thing is when i purchased this SMPS they told me its 450 watt SMPS and support your gig..then after few weeks my system restart unconditionaly/anytime/without beep sound/
sometime its restart 3 or 4 times while bootup..
so i go to computer shop with this pb they told me may be some wire loose ..they fit all wire and pc work 2 days good the again restart pb happening..and coz of this restart pb i lost my GPU broken..
so yesterday i call to SMSP (iball company) customer care office and asked to them exactly power of SMSP ..so they told me SMPS give 250watt ..and output is 230watt..not 450watt..
so right now i m using my pc without GPU but its still restart
so i need to know what exactly is pb
thanks a lot
Well, I ran one of the calculators for you. It yields a minimum requirement of 229W - which your PSU provides - but it also recommended a 500W PSU. Remember, though, that these requirements will likely go up when you replace your graphics card; today's boards are much more power hungry. I would recommend that you look for a Bronze 80+ certified 500W PSU...
Now, all that said, your other information has me thinking that your problem is not the PSU. It sounds more like you have a component on the board that is failing under load. This could be a thermal issue (I have seen many failing parts that run ok when cold but fail when heated up. Consequently, I would recommend a motherboard replacement as well...
I would add that there is always a possibility that it is not the motherboard itself, but some component - like memory DIMMs - that is plugged into it...