Does Watts in a psu matter if you want to run a good video card?

Martynas Jankus

Honorable
Dec 23, 2013
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10,530
Hi.
I am looking for a cheap psu that could run a 2 4pin motherboard and also a 2 6pin Zotac GTX 560.
I am not sure if the more watts you psu has the better because i had a Tesla 750w psu which burned.
My question is what determines if a psu can support a good motherboard/video card?
 
Solution
The wattage rating on the sticker doesn't matter but the actual amperage and watts that the PSU can produce in real world usage does matter. This can be misleading because at the very low end PSU's make 750 watt claims which may be true if the power supply was in a fridge in Antarctica but in real world testing where heat is involved they will handle much less wattage. Stay with reputable companies like Seasonic. Yes it will cost more but that shouldn't surprise anyone since quality always cost more.

These two sites do real hot box testing to see what PSU's are really made of. Pick one that meets your needs that they rate highly. In your case a single GTX 560 will not need a PSU larger than 500w if the PSU is high quality...
The wattage rating on the sticker doesn't matter but the actual amperage and watts that the PSU can produce in real world usage does matter. This can be misleading because at the very low end PSU's make 750 watt claims which may be true if the power supply was in a fridge in Antarctica but in real world testing where heat is involved they will handle much less wattage. Stay with reputable companies like Seasonic. Yes it will cost more but that shouldn't surprise anyone since quality always cost more.

These two sites do real hot box testing to see what PSU's are really made of. Pick one that meets your needs that they rate highly. In your case a single GTX 560 will not need a PSU larger than 500w if the PSU is high quality.

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Review_Cat&recatnum=13
http://www.hardocp.com/reviews/psu_power_supplies/
 
Solution
What determines the quality of a PSU is the DC output. ATX specifications say the DC voltage output from a PSU must be +/- 5% on the positive voltage rails and +/- 10% on the negative rails, they also have specifications about ripple and noise (variants from true DC voltage). A high quality PSU will keep the voltage very close to what is suppose to deliver while controlling ripple and noise
PSU's are a highly unregulated market and wattage descriptions cannot always be relied on as being accurate (without a little extra research), Gabriel Torres of Hardware Secrets explains some of that here http://www.hardwaresecrets.com/article/Why-99-Percent-of-Power-Supply-Reviews-Are-Wrong/410 (Mr. Torres is one of the better PSU reviewers out there IMO)
Here's what I suggest you do to find a quality PSU for your system (500W or greater would be fine), go to http://www.realhardtechx.com/index_archivos/Page541.htm and find a highly rated PSU there or (probably easier) find a PSU you are interested in and then check out it's reviews from that site's links. Personally, if I can't find a good review for a PSU there, I won't consider it for use.
I'll suggest looking at brands such as Corsair, Antec, Seasonic, Enermax (although usually pricy) to start