How much WATT needed for CF

Donten

Donten

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Op_Valkyrie said:
U lurker sia!!

mobo-less now bro, hope to start soon.....my box starting to collect dust...later like mr lee.... haha..

so any comments on the nvidia vs amd war currently?
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Whoever comes out with the better dual gpu card I will support since I intend to go itx.
 
royfrosty

royfrosty

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devilwahaha said:
Where you learn such things from :s11:
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Go read up more on tomshardware forums.

Its not good to load a PSU more than 60%. Cause once a PSU reaches a certain years once the PSU could not attain or produced that amount of watts needed it will just explode. Recommended for dual GPU config the best is between 750w to 850w. Giving you head room for about 40%. Even in the long run if it degrades it still can upkeep whatever power is needed.

Not good to just take a margin headroom like 650w for 2 gpus. Although it can still run, but once it cant handle then it would probably fry the rest of the components together with it.
 
Maeda_Toshiie

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royfrosty said:
Go read up more on tomshardware forums.

Its not good to load a PSU more than 60%. Cause once a PSU reaches a certain years once the PSU could not attain or produced that amount of watts needed it will just explode. Recommended for dual GPU config the best is between 750w to 850w. Giving you head room for about 40%. Even in the long run if it degrades it still can upkeep whatever power is needed.

Not good to just take a margin headroom like 650w for 2 gpus. Although it can still run, but once it cant handle then it would probably fry the rest of the components together with it.
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TH forums...? Sorry, but no.


60% max loading is only applicable for:

1. Maximize PSU efficiency for 24/7 peak loaded systems (CPU AND GPU). Eg. coin miners.
2. Cheap ass power supplies. Proper PSUs are overengineered to supply the rated wattage over the typical number of years of usage. If Seasonic can give 5 years warranty for their PSU, their PSU are capable of supply that rated wattage for that 5 years.

The amount of PSU oversizing is ridiculous at 60% max load.
 
D

devilwahaha

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Maeda_Toshiie said:
TH forums...? Sorry, but no.


60% max loading is only applicable for:

1. Maximize PSU efficiency for 24/7 peak loaded systems (CPU AND GPU). Eg. coin miners.
2. Cheap ass power supplies. Proper PSUs are overengineered to supply the rated wattage over the typical number of years of usage. If Seasonic can give 5 years warranty for their PSU, their PSU are capable of supply that rated wattage for that 5 years.

The amount of PSU oversizing is ridiculous at 60% max load.
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But roy said it, it must be true :D
 
Maeda_Toshiie

Maeda_Toshiie

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Oversizing is fine, especially for overclockers. However, the question of size goes back to

1. Usage pattern.
2. Maximum peak power usage by system (system power draw)


1. Most typical users use their machines for more than gaming, which is the most intensive task for most people (except dedicated coin miners and people don't run HPC servers at home right? Nor are there folders, SETI, and whatnot participants in SG).

However, people don't game all the time and a significant amount of time is spent browsing the web, where the typical power draw is ~100W (less for non-overclocked Intel machines). This means that for a significant part of the time, the PSU is operating at the low end of the PSU efficiency curve. The bigger the PSU, the further off at the end you are. The PSU efficiency question is no longer clear cut for the maximum load to be at 50-60% of rated wattage.

2. There are a whole lot of arguments on this. Even Intel stated that the best way is to measure it off the wall (and then account for PSU efficiency, see Intel's white paper on this). Of course, this does not mean a $20 kill-a-watt but a >$100 industrial grade meter (oscilloscopes are overkill except for reviewers).

Killawatt accuracy (and many other threads): Kill-A-Watt accuracy test - jonnyGURU Forums

Yeah, take your kill-a-watt readings with a grain of salt because they can be wrong.

So how do PSU calculators work? Mostly by using TDP numbers. However, given the silicon lottery, the TDP given by AMD and Intel are all actually cap values, not even for each specific model, let alone each specific piece of silicon. Power draw of CPUs tend to be lower anyway due to lack of applications that can fully load all cores (outside of power viri)

Another point is this, not all software (esp. games) can induce maximum draws. Even stress testing synthetic loads using IBT, P95, OCCT, etc can result in somewhat different maximum power draws. Games usually do not draw as much power as synthetic workloads, nor do so for the entire gaming period.


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

I read OCN, [H], AT, and JG. I don't think the guys who do PSU reviews can get that wrong, especially those on JG.
 
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huasze

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calculate lor.

lets be scientific and not listen to hearsay.
too often people overbuy massively on the PSU.
when the vast majority of PSUs are overloaded, they will shut down.
the ones with no overcurrent protection which will smoke out are not easy to find---remember the iCUTE psus?

when assessing your needs, its not the total PSU watts, but the watts(power) supplied on the 12V rail.
since P=IV, you want to have a good idea of the current draw.

Calculations:
1. CPU is 130W TDP(if you're on some power hungry cpu)---10.83A
2. HDD is 11W for a raptor at max write(half for most other drives)---0.92A
3. motherboard max 40W(can only run with CPU, so should usually be considered with the CPU, but lets just separate it in this case)---3.33A
4. RAM is 3W per Dimm. if you have 4, its 1A
5. GFX card is 257W max for a 280x on bitcoin mining according to tom's hardware. I do not know if the 257W is a derivation, or a real world power draw. if it is a real world power draw from the socket, then the resulting wattage would be below 257W depending on PSU efficiency. let's just take 257W in any case, meaning---21.4A
6. Fans. the amperage of fans are usually written on them, say 5 fans at 0.2A on 12V---1A

Adding 1+2+3+4+6=17.08A
Take a Super Flower Golden Green 750W with 60.5A on the 12V rail.
60.5-17.08-21.4-21.4=0.62

This looks very close to 100%, but it won't be the case, because there will be no real world scenario where a person will be benching with cinebench and playing BF3 plus doing full writing on the HDD while transferring videos and looping prime 95.
The real power draw at max real life use will be closer to 80% load.
So, in conclusion, you do not need anything more than 60.5A on the 12V rail(or multiple rails added up to 60.5).

However, if you are going to be benching, overclocking, and doing mega stress tests on your CPU+GPU at the exact same time, then you may cause shutdown. If you might be doing that, then by all means spend on a 1200W PSU with 99.9A on the single rail like the Leadex Platinum 1200
 
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