if we buy a psu having 350 watts how can we test wether it is 350 watts and not less 300w .how do we know that we are not cheated. in my country we get psu with stickers having the wattage specification

Hello gotodreams...(I'm in search of unanswered posts). ;)

If you don't mind me asking, what Country are we talking about here?

You are quite right, Manufacturers labels can be very deceiving. The "Wattage rating" may not mean a thing...Just like a Stereo advertised as "Wow! 500 WATTS of POWER!"
What's important, among other things, is how many watts RMS per channel it is....most likely around 100w per Channel in my example).

The same is true of Power Supplies. What's important is not so much the "claimed" overall "Wattage" rating, but rather the output power supplied to the individual Voltage rails, and maximum output load the combined rails can handle.

There are a couple of links below- (getting a bit outdated now, but will give you an idea what I'm talking about).

http://www6.tomshardware.com/howto/20021021/index.html

http://www.firingsquad.com/guides/power_supply/default.asp

The reason I ask what Country, is I don't know what is available to you there but your best bet, if possible, is to stick with a good quality PSU (Like ANTEC of ENERMAX to name a couple...Opinions will vary).

Generally, the better PSU's will clearly state the maximum output for the individual Voltage rails right on the outside of the Power Supply rather than just a big sticker that claims "500 Watts" for example.
You have to be careful for sure...No question there is some real junk out there.

Best bet is to do a little research, read through these and similar articles, and then, even if some of the better brands aren't available to you, at least you'll be a little better prepared to ask some questions when you go to buy one.
Good luck.

i stay in india , mumbai city. here we have to go with the stuff that is available and it is mostly from china rarely we get european stuff. i wanted a psu with 400w for my p4 machine. previously when i assembled my pc i got the psu with the case but it was just 300w. then i went to the market searching for a 400w psu.many didnt have a 400w they just had 300w. one shop where i asked said a 400w will cost me 1700 rs and a 350 will cost me 600rs. other shop said they had 400 watt but it will cost me600rs. then i bought it from a shop which said that a 400w will cost me 700 rupees. it was in a nice packing and seemed original so i took the risk . when i came home i visited the site printed on the psu box . it was "colors-it.com" . if u want u can visit that site. i checked the site for the model no which was printed on my psu . it was 300u----- (and something) but i was not able to find it any where on there site. later i learnt from a table that 300 u refers to 180w i just could not understand what was all this. but the sticker on the psu i purchased for similar to the companys' . but on the sticker it was written 400w it seemed printed later. i emailed the company about this and im still waiting for a reply since one week . so i thought of writing in the forum if any tool or way was there to check the exact wattage of the psu and not get fooled again

To make sure I don't get burned, I stick to known good manfacturers and I shop by model number. I've never heard of colors-it or their PSU's. Looking at the site, I see their models number don't refer to the output wattage. That's something you have to be careful of!

Do like jabarnutcase suggested and only buy PSU's from manufacturers like Antec and Enermax. At least their model numbers reflect the wattage. :rolleyes:

gotodreams, if you have the ability, you should shop on line as it sounds like the shops in your area are not very trustworthy:eek: If you can not find the quality products recommended, then that would be a second reason to shop on line.

Here is a GOOGLE SEARCH (http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=power+supply+tester) for power supply testers. The first few are simple testers to let you know it is supplying voltage on all leads. I think you would need a good multimeter to acctualy test wattage. Rated wattage is also a "Peak" number and may not be seen in a test without the proper load.

Good luck
Frank

thanks to all. i wrote this as i wanted all the novice buyers to be careful. in my country duplicacy is at its highest. its really hard to get an original product at my place.i really doubt if someone might be doing online shopping for it products. even if i wanted to send cash by remittance i cant send as its not available in my country. bad luck