clarification on psu

[random44]

Hi All,

Two question on psu, if I get a 750 watt and the system in not under full load will it still draw 750 watt per hour ?

does anyone have a like to a good article about psu and their basics so can gain some more knowledge in this area?


many thanks for your help.

 

[EarthDog]

A PSU only draws what it needs to.

Did you look at the sticky's in this section? There are great threads there.

This one, though old, will give you a baseline: http://www.overclockers.com/forums/showthread.php?t=458204

 

[Luke1978]

Why the crap PSU/GPU/Mobo????

CPU: AMD FX-9590
Motherboard: MSI 970
RAM: 8 (2x4) gb 1866 mhz / 9-10-9-27
GPU: GTX 650 2GB
Case: ASPIRE X-CRUISER
PSU: Cheap ebay 500w
Storage: SSD 240gb extreme pro

 

[Blaylock]

The MoBo and PSU he had purchased prior to joining us. We are now trying to square him away in the correct path.

 

[random44]

yes got the evga 750 based on advice in here.

gpu I am happy with as it seemed that my cpu was bottleneck for my game

board , am happy so far.

also does psu get the hot air and blow it out?

how can I monitor its temp ?

in here it says the psu can work at up to 50 degree .

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story2&reid=380

how do I know the current temp at anytime to avoid fire?

 

[Blaylock]

PSU will self regulate its temperature. No need to worry there. In your Apevia case the PSU will pull in warm air from your case and exhaust hot air out the back. I generally don't include this when looking at Pos/neg case pressure. ( I know you've been looking into this too) However, you certainly could consider it.

 

[EarthDog]

also does psu get the hot air and blow it out?

how can I monitor its temp ?

Yes.

You cannot monitor that PSU's temperature.

You keep your case temps down with adequate airflow which is what you are trying to do in one of your other threads...

 

[random44]

sorry for asking so many questions but reading around two questions came to mind which I am trying to work out answers.

looking at below the psu I am buying is single rail and reading couple of articles multi rail is better , am i correct in saying the psu is single rail?

http://www.jonnyguru.com/modules/NDReviews/images/EVGAG2750/DSC_6418.jpg

also I understand a wall socket can provide around 13amp and some of the amps here are as high as 60 to 70 so am I correct saying the power is multiplied by capacitor and other electrical companents to get 60 amp ? that is a lot of current and can kill straight away .

also 750w means it will draw 750w or less each hour so if my electricity is costing me £0.11 per kwh then each hour of my pc running assuming full 750 load should be less than £0.11?

 

[EarthDog]

looking at below the psu I am buying is single rail and reading couple of articles multi rail is better , am i correct in saying the psu is single rail?

There is a sticky thread in this section that talks about dual vs single... read that. But to answer, it really doesn't make much of a difference. Read those stickies man!! The answers are in there!

13A @ 120v versus a PSU/PC uses 12v @ xx amps. Two different things.

 

[Blaylock]

This is the place and time to ask questions. So no apology neccesary, this is how we learn.

Single or multiple rails is one of those age old questions. Today single is considered the better way. I believe the ave household outlet is 15 & 30 AMPs not 13, but I'm no expert on this.

 

[EarthDog]

1500W is common (so 15A @ 120v). Except for say your washer/drier/stove/ and maybe another circuit or two.

 

[random44]

so my current cheap psu has a lot of amp on 5v (48) which I understand back in the days there was most reliance on 5v .

now I have my cpu/gpu and motherboard. if my cpu is 125w, does my mb also pulls 125watt so 250 watt ? then my gpu may pulls go knows but lets say 100 so assuming my mb is also pulling current then I am on 350 on 12v rail .

now my rail been 19amp max and my devices pulling around 29amp then I am already over it and can potentially damage the board so shall leave it until i get my psu.

theoritically , is my calculation correct?

 

[EarthDog]

Your calculations are not correct in theory or reality.

*Your mobo does not pull 125W...
*Your GPU pulls 65W.

 

[random44]

ok , i did a max calculation. I just want to play game and it might be next week before i get the psu .

I am having a flying lesson and want to practice.so no planing to oc but rather trying to work out if I can run it at stock imagining the system is under full load.

so if my cpu is 125w , how do i know what my motherboard is pulling ?

then how do you know what my gpu pulls?

I am dying to play and just need to assess the risk


just reading around it says it will use 5v rail if 12v is not available for cpu .

 

[EarthDog]

so if my cpu is 125w , how do i know what my motherboard is pulling ?

You dont really, but it is not remotely close to what that CPU is pulling even at stock.

then how do you know what my gpu pulls?

Reading the internet. GPU's have a TDP (Thermal Dynamic Power) which is how much heat the card needs to dissipate. While this is not an exact measurement of power use, it is a close enough value to hang your hat on. Any review worth its salt mentions this value which is defined by the manufacturer of the card (AMD/NVIDIA)

just reading around it says it will use 5v rail if 12v is not available for cpu .

That's a new one... not sure if that is true or not. I do not see how it could honestly.

 

[random44]

so around 6 amp my gpu and 10 cpu then that is under 19 .

would the ocp kick in and shutdown the system if I go over 19 hence protecting my system ?

apart from cpu and gpu what else is on 12v?

 

[EarthDog]

I have no idea as we have no idea what your PSU is, find a review about the platform and see where it kicks in.

But only 19A on a 500W PSU? LOL, yikes. It should be around 36A or so. That PSU is really garbage and old.

As far as what else, the motherboard does use some power and some is from the 12v, what specifically, no idea. the bottom line is, on a cheap arse PSU like that, coming CLOSE to maxing it out is a TERRIBLE idea.

 

[random44]

my psu

http://www.adverts.ie/desktop-hardware/mhel-500w-atx-power-supply/163602

 

[Mr.Scott]

48a on the +5v rail tells me that this is a very old ATX spec. PSU. This was made for use on mobos before the 4 pin +12v was used. It's totally inadequate for todays hardware. Most of the draw today is on the 12v rail. Back 10 years ago it was on the 5v rail.
You need to replace that before you kill something.

 

[ATMINSIDE]

You need to replace that before you kill something.

And/or set something on fire...

Because that's what your "ebay 500W" is. A fire hazard.