RE: PSU Recommendation 2014

[m3 th3 last]

RE: PSU Recommendation 2014

Hey guys, i need to clear a few question i may not understand about PSU.

On theory, is operating at the PSU optimal load is the most power efficient?

Say a normal gaming rig(whole) pull about 375w at it's peak. Which require roughly at least a 500w psu assuming at 80% efficiency. (almost at load )

Compare this to having a 700w psu that may be running at it's optimal range (Normally higher efficiency) maybe say 87%.

Which will be pulling less power from the wall? Less electricity bills in theory.

Into products, i notice recently a lot of recommendation for seasonic s12g 550w, is this better compared to FSP 500w model?

Thanks for your replies.

 

[Felfirez]

In theory, PSU is most efficient running at 50% load there about but in modern PSUs the difference is negligible. The more efficient the PSU the lesser heat it gives out and better quality materials, the longer it'll last.

In terms of electricity bill savings, a few dollars a year between bronze and gold unless you're going 24/7 mining.

S12G is modular. FSP Aurum 500w I presume you're comparing with is non-modular. Both are very good PSUs

 

[twasken]

Can take a look at how the PSUs are 80+ Certified here.

Most PSU are like Felfirez said, most efficient at 50% of their rated capacity. For 80+ Gold PSUs, their efficiency mostly above 90% between 40% and 80% load, so in terms of electricity bill savings, really not a lot.

Some graphs from some reviews to better clarify how the efficiency looks like:

Spoiler

Source: FSP Aurum Xilenser 500 W Review | techPowerUp

Source: Seasonic G Series 550 W Review | techPowerUp

 

[Strikk]

Are there any detrimental effects for having too much watt? I bought 700w when the 600w oos everywhere. Im only on single gpu configuration.

 

[zetken]

actually when u have 1000w psu. and only have one gpu config. the power saving is roughly highest. due to 50% is always their peak in most cases.

thats what i read about. haha. i guess there are more expert around here.

 

[Maeda_Toshiie]

Before massively oversizing your PSU based on the 50% rule, consider the following:

1. How many hours do you spend using your computer such that it is at peak load? Contrast that to the number of hours where the PC is at near idle; for example the time spent where the GPU is not under heavy load (including the time you spend watching 1080p video with CPU decoding, even if they are insane over the top encodings). The only possible situation where the CPU load is comparable to the GPU, is when you heavily overvolt to overclock, or use an AMD space heater. Even then, you need to fully load all cores to hit the maximum TDP.

2. What is peak load? TDP of CPU+GPU+mobo+motor-spin-ups? This is already an overestimate of what your PC can consume outside of 24/7 folding/ mining/ video encoding, etc. Games are not power virii. I say this because this isn't OCN or [H] with folders with folding rigs.

3. Power efficiency is NOT DIRECTLY RELATED to how many watts the PSU can output. A 500W at 80% efficiency (at peak wattage) PSU is supposed to be able to supply up to 500W at the rated temperature, for the relevant voltage rails while drawing 625W from the wall. Buy a PSU that is capable of supplying the stated wattage at the stated operating conditions.

---------------------------------

OCN, for all its trolls and fanboys, actually have stickies that cover the basics of PSUs.

 

[m3 th3 last]

Hey guys thanks so much for the input.

As noted in the tomshardware quarterly PC configuration.

A i7-4770k with a 780ti would only draw 462w o/c'ed. (at wall)

A i3-4130 with a 770 would only draw 296w o/c'ed. (at wall)

So we roughly know what amount of power is required at it's peak. But of course in actual operation it would hardly be hitting those limits or only for short spike.

Higher efficiency leads to lower power lost in transition process, lower temperature, and indirectly the lifespan of the PSU. This efficiency comes from 2 area. One a better built PSU(e.g. 80+ gold). Two PSU operating at it's optimal load (50-75%).

So combining the two information, it's good to make 25%-30% headroom for maximum wattage combine with a gold certificate PSU. This will ensure the highest efficiency.

In real terms, FSP 500w and 600w difference is only 10 dollar, if i'm correct based on best bargin listing. It's always better to buy that 600w cause in the length of say 5 years, 600w would save you more electric bill as compared to the 500w. (throw out sufficient out of the picture first)

Please critic my assessment

 

[Alphas]

Just buy a psu with 20% overhead of the total system power. Calculate the total power for each hardware and add 20% more. Anything more is just overkill.

So the system requires 500w, then a 500x1.2=600w psu is more then sufficient. It is useless getting a 1000w psu when most of the time the PC is idle, taking less than 100w.

In fact the efficiency of the psu drop significantly as the load decrease, some psu is only 50% efficient at 20% of its capacity. Not only are u wasting on getting an overkill psu, u are also spending a lot on less efficient load capacity. Since the PC is idle most of the time, alway stick to system power=80% of the psu power rating.

 

[hohohos]

I'm too lazy to calculate wattage...when i build my rig
,i'll just slap a 600w psu inside

 

[Alphas]

Dun need exact wattage la, just approx in interval of 50w. My i5 CPU with 3x Hdd and 2x ssd and 2x gtx670 SLi only requires 620w psu, running it a year ago.

 

[12122012]

As noted in the tomshardware quarterly PC configuration.

A i7-4770k with a 780ti would only draw 462w o/c'ed. (at wall)

A i3-4130 with a 770 would only draw 296w o/c'ed. (at wall)

note that new coming Maxwell gpu will draw much less power.

 

[Alphas]

Hey guys, i need to clear a few question i may not understand about PSU.

On theory, is operating at the PSU optimal load is the most power efficient?

Say a normal gaming rig(whole) pull about 375w at it's peak. Which require roughly at least a 500w psu assuming at 80% efficiency. (almost at load )

.

That is wrong, a 500w psu is suppose to deliver 500w power, if it is 80% efficient, it will draw about 500/0.8=625w at wall socket.

 

[Maeda_Toshiie]

note that new coming Maxwell gpu will draw much less power.

It may actually mean that the GPUs will be more powerful at the same TDP. I highly doubt Nvidia will be releasing cards with power consumption substantially lower than the present generation. It is more likely that Nvidia will maintain the TDPs, especially for the high end/ flagship cards while maximizing performance.

 

[m3 th3 last]

That is wrong, a 500w psu is suppose to deliver 500w power, if it is 80% efficient, it will draw about 500/0.8=625w at wall socket.

So it's not the other way round?

Okay i guess i need a 600w psu to run it at the rig's most efficient power requirement.

 

[12122012]

It may actually mean that the GPUs will be more powerful at the same TDP. I highly doubt Nvidia will be releasing cards with power consumption substantially lower than the present generation. It is more likely that Nvidia will maintain the TDPs, especially for the high end/ flagship cards while maximizing performance.

It is interesting to note that the reference graphics card based on the GM104 is projected to sport only one 6-pin PCI Express power connector, which means that its maximum power consumption will be 150W (75W over PCIe slot and 75W over power cable).

First rumoured specs of GeForce GTX 880/GM104 published | KitGuru

 

[m3 th3 last]

thats quick

 

[12122012]

So it's not the other way round?

Okay i guess i need a 600w psu to run it at the rig's most efficient power requirement.

let say your pc need 253.22w and your psu @91.50% efficiency, it will draw 276.73w from the wall.

 

[m3 th3 last]

let say your pc need 253.22w and your psu @91.50% efficiency, it will draw 276.73w from the wall.

That i understand.