PSU: Output vs Rating?

[rekjl]

Hello everyone

I am building my new pc soon, and while deciding which PSU to go for, there has been one question that I has got me curious.

Would you guys go for a PSU with better Rating (Silver or Gold) or one with a higher output?

For example, the XFX XXX Black Edition 750w vs the Cooler Master Silent Pro M850

The XFX gets fantastic reviews, and a silver rating. The Cooler Master on the other hand gets good reviews, but only has a bronze rating. But over here, the XFX actually cost moderately more than the Cooler Master.

The XFX can handle higher loads much better than the Cooler Master, but in a same scenario comparison, won't it be minimal?

For example, at the typical 85% efficiency of the Silver Rating under full load, the XFX will be able to pull out 660w or power. The Cooler Master with the typical 81% efficiency under full load will be able to produce 688.5w.

Won't this mean that with the exact same equipments, the Cooler Master because of the 28.5w extra limit will actually be using less load compared to what the XFX has to produce to power up the same equipments?

The glarring difference between the two PSU is that the XFX can handle 50c compared to the Cooler Master's 40c. Is this difference enough of a difference to pay more for it?

In terms of reliability, the Cooler Master as well as other more budget brands are also considered good and reliable PSUs.

Won't this mean that getting a good high power psu is equally as good, or better in some cases, to getting an excellent lower power psu?

I am still new and learning about the components of the computer, so if I am understanding this wrongly and there is a glaring mistake to what I've written, please correct me to this.

Hope everyone can share their thoughts and knowledge on this with me.

 

[evilgenius134]

Really depends on what load you'll be putting on it. For single card configurations even the 750W would be overkill. For dual cards both would seem to do fine, but even 750W would be pretty good.

Gives us information of your system you'll be powering with this and we can advise further. It really depends on what you'll be using. But I definitely go for higher ratings as I have Seasonic X-650 which is Gold rated (expensive though).

 

[rekjl]

Thanks for your reply evilgenius134.

The new build will be:
i7 2600k (oced to somewhere around 4.8 or higher if stable)
Gigabyte GTX560 SOC 950mhz version ( planning to SLI it at end of year)

The other components are mostly the standard compenents like sound card, blu ray combo drive, 1 hard drive (+1 in future), cpu cooler and such, but many people say that these don't really eat much power.

I've read that a 700w psu is sufficient, but most of the 700 range available are either very good (more expensive than the M850) or below average.

In terms of price, it is slightly more expensive, but if it really is much better, I won't mind spending extra. But will I actually feel the difference? Haha I guess if my computer can feel the difference in a positve way, it is a good reason.

 

[obsidian86]

you got it backwards

the xfx can provide 750 watts

and the coolermaster can provide 850 watts

the efficiency rating is to do with how the power supply converts current and the loss during the conversion

say your psu is exactly 80% efficient at a load of say 750 watts being pulled from your power supply at 80% efficiency the power supply will draw 900 watts from the wall to provide that 750 watts,whereas that 150 watts is lost during conversion

but if your psu wat 90% efficient for it to provide 750 watts it will only pull 825 watts from the wall with higher efficiency there will be less wattage wasted during conversion

now if your psu was 50% efficient and it was putting out 750 watts you will be drawing 1125 watts from the walll to only put out 750 watts

the cooler master silent series are the only series worth a look the rest are crap ,as for xfx all the power supplies from them are decent

 

[ko888]

I would choose the XFX Black Edition P1-750B-NLG9 over the Cooler Master Silent Pro M RS-850-AMBA-J3.

It runs cooler because its power conversion is more efficient. I would also choose the XFX's Seasonic design over the Cooler Master's FSP design.

During Hardware Secrets' test reviews of both units they were able to pull a total of 936.1 Watts from the XFX 750 Watt Black Edition during Overload testing (66 Amps on the +12 Volt rail) while they were only able to pull 894.9 Watts from the Cooler Master Silent Pro M 850 Watt (64 Amps on the +12 Volt rail).

Either PSU is more than enough for two GeForce GTX 560 Ti in 2-way SLI mode and any overclocking of CPU and GPU that you may want to do.

 

[leon2006]

Learn how to calculate your load. It provides you with definitive information base on calculated load. Its a real number not somebody else estimate.

http://www.antec.outervision.com/

 

[Outlander_04]

For that rig you need 500 watts maximum

If you plan on SLI later then 600-650 watt will be more than enough

 

[rekjl]

Wow! Thanks obsidian86! I really got that messed up, thanks for helping me understand what the rating really does!! Haha ya, people have been telling me to stay as far away as possible from the GX series.

ko888, yup, that is the sentiment I get from most people, but I had no idea you would be able to pull more power from the XFX!! Thanks for that!

Thanks for that link leon2006! It really has helped me. Thanks to that, I have more confidence in what power output psu to go after. (fyi my requirements were just under the 650w mark)

Thanks Outlander_04. Yup the calculator leon2006 provided concured with your advice.

Thanks everyone, this has really helped me decide which power supply to go for! My first choice will be the Seasonic X-750, then the XFX 750, then the Silverstone Strider Plus ST75F-P, then if all of them suddenly happens to be out of stock at the same time (......haha it could happen ) then I'll go for the M850 or the Silent Pro Gold 800w.

Over here, Corsairs are really expensive. The HX750 cost even more than the Seasonic X-750.

Again, thanks everyone!!

 

[obsidian86]

Its a pleasure to help.and the over rating on the power supplies are just a safety factor for surges and shorts.and it has a cut off point so you dont over load the psu

 

[rekjl]

Best answer selected by rekjl.

 

[obsidian86]

Thank you