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Noob powersupply question

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March 11, 2010 3:55:55 PM

:hello: 

I have a Coolermaster Realpower M700 powersupply and im wondering if its enough for my heavily overclocked rig.

The beast! Rig.

Core i7 920 @ 4Ghz HT on
Gigabyte X58-UD5
Gigabyte HD5850 @ 1000/1200
3 x 1GB OCZ Triple channel 1333mhz 7-7-7-21 @ 1200mhz 6-6-6-16
Samsung Spinpoint F3 500GB
LG DVD ROM Drive
Coolermaster Real Power M700
Coolermaster HAF932
Custom GPU and CPU Water loop
5 x Fans

So I've noticed when I overclock my HD5850 and play a game my PSU will whine like a little sister really loud and annoying. I noticed that under heavy load my 5850 eats almost 42amps (according to GPU-Z)

My PSU has 4 12V rails (Here comes the first thing I'm not sure about) and my card uses 2 x 6pins provided by the PSU, So I take it that my card uses 2 of the 4 rails?

The 12v rails are rated at 19A each and allow for a total draw of 624 watts. So if im right in my assumption then my PSU can only give my GPU 38Amps (2 x 19) and as I mentioned before it eats nearly 42 amps under heavy load.

So that lead me to believe that the whining noise is becasue my PSU is working harder than it should in an attempt to provide enough amps. (?)

Really would appreciate some info :love: 
a b B Homebuilt system
March 11, 2010 3:59:45 PM

the real power is a lower range psu built by a substandard company i wouldn trust it as far as i can throw it
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March 11, 2010 4:06:20 PM

Yeah thats great, but I've brought it now :lol: 

Am I right in my assumption?

(P.S can we not have anymore " Coolermaster sux man, Corsair FTW dude....")
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a b B Homebuilt system
March 11, 2010 4:38:17 PM

nope this is a serious post the real power m700 is built by acbel, google it if you wanna they dwell in the lower regions of reliability

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March 11, 2010 4:50:03 PM

Ok I got it, My coolermaster PSU is low end, unreliable, cheap and only good for a paper weight, but can you please answer my orginal questions, I would be very greatful.
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a c 84 B Homebuilt system
March 11, 2010 5:05:08 PM

Your PSU is whining under heavy load because, as a low quality unit, it's fan is having to work really, really, really hard to keep the unit from bursting into flames because your build is drawing so much power from it. Just because it SAYS it can provide 19A on all 12V rails doesn't mean it can.

Check out JonnyGuru.com for a review (if they've done it), and you'll find out exactly how much it can provide. My guess is that it's meeting the bare minimum for the 5850...
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March 11, 2010 5:22:16 PM

Well I've done some research and it appears that the whining is because of voltage going through the coils known as "Coil whining"

I'm not experiencing a loud fan noise at all, the noise is VERY high pitched.

I'm I right in saying that my 5850 uses 2 out of the 4 12V rails because it uses 2 x 6pins???

According to the calculator I need just 482 Watts, thats with 100% TDP and 15% aging. But doesn't say anything about amps.

I've checked out reviews for my PSU, trouble is that it came out in 2007 and so the systems they use to check the PSU with are old and not very demanding.

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a c 84 B Homebuilt system
March 11, 2010 5:30:03 PM

To be honest, I'm not exactly sure how the rails are split up. I'd be amazed if it was one rail per 6-pin connector though.

The main thing about the wattage calculators are that they tell you how much wattage you need, not what the unit can provide. You could very well buy a 700W unit, but if it's poor quality, it could only put out 300W to the useful parts. Just because a PSU says 700W, doesn't mean it can actually do that.

Older systems are actually more demanding on PSUs than newer ones. The newer manufacturering tech for CPUs (45 nm now, 32 nm for the upcoming 6 core CPUs) mean they use a lot less power. The same is true for the GPUs. I'm looking forward to what they think of next to do a realistic test of PSUs to draw out their full potential.
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March 11, 2010 5:46:40 PM

So my PSU has 4 x 19A = 76A Total and 700W continuous power(when it was new)

My 5850 at 1000mhz Core and 1200mhz mem uses 42A under 100% load. So that leaves me with 34A for everything else. Now I have no idea how much for example my Core i7 uses

So....I really don't know what to do. Many people say that they have RMA'd there PSU because it whines and then they got a different brand PSU which didn't whine. But it seems like a total gamble.
I feel partly inclined to buy a new PSU anyway as many people have said (not only now but in the past) that coolermaster PSU's are of poor quality, it seems hard to find some solid evidence of this though.

Here is a video of the sort of whining that I'm talking about, notice its a Corsair PSU, so it seems it happens to even the best quality powersupplies.
http://www.youtube.com/watch?v=C4d23F2jehQ
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a b B Homebuilt system
March 11, 2010 6:05:32 PM

watts=amps x 12

amps= watts / 12
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March 11, 2010 6:14:12 PM

wow im so confused.

700W divided by 12 = 58.3 Amps.

This review http://www.overclock3d.net/reviews/power_supply/cooler_... Says it has a total combined load of 52amps

But my PSU sticker says it has 19A on each of its 4 12V rails and 25A each on the +3.3V and +5V

Anyone care to explain this, (Sorry complete powersupply noob.)
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a b B Homebuilt system
March 11, 2010 6:21:40 PM

You can't just add up the 12v rails (four 19A rails does not mean you have 76A). You have to use the formula to get the actual amp rating.
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Best solution

a b B Homebuilt system
March 11, 2010 6:33:24 PM

Lets see
(1) the winning is probably a coil or a transformer with loose windings that are vibrating @ 60 Hz (also have some coils with 20 -> 40 KHz). The PSU SHOULD NOT Whine
(2) Where did you get that 42 Amps. Forget that 42 Amps in your org post 42 x 12 = 504 W A 5870 at max load is only approx 161 W ( requires about 13 ->14 Amps), But don't forget your CPU uses the +12 V rail also.
(3) My i5-750 @ 3.6 w/5770: Draws only about 300 Watts @ max load, so add alittle for upgrade to 5850 and a I7 @ 4 GHz- Your system is probably no more that 450 Watts while gaming, if that much.
(spec can be very deceiving) If you add up the combined wattage you will find they exceed PSU ratings. In maey cases if you calculate the max wattage for just the 12 V rails, they will exceed the wattage rating. You then need to look at the temp for the ratings - OPPS many do not provide that, They don't want you to know that it was at sub-zero (A little exaggeration (Louy speller).

There is a chart which ploaces PSU's in tiers, Recommend you use it to select your New PSU, Which I recommend you do ASP.
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a b B Homebuilt system
March 11, 2010 6:39:16 PM

where does a 5870 use 160 watts max load?
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a c 84 B Homebuilt system
March 11, 2010 6:44:44 PM

I think RetiredChief meant a 5850, as that's what the OP is using...
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a b B Homebuilt system
March 11, 2010 6:45:04 PM

Bingo, If you add up all the Power (192, 624,17,10 = 842 Watts, gee you get an extra 142 watts out of that 700 Watt PSU - Don't think so

On the 12 Volt rails: each rail can provide up to 19 Amps, But not all. as you pointed out +12 V is limited to 624 W ( total of 52 Amps ). What that means is that if Rails 1 and 2 were to draw 19 Amps each then rails 3 and 4 would be limited to no more than 14 Amps ( ie Max of 7 Amps each if evenly split.)
More realisticly you would have abnout 16 Amps max on 1 and 2 and 10 Amps on rails 3 and 4.
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March 11, 2010 6:58:47 PM

ok so it seems that a 5850 uses roughly 150W under load, I'll add another 50 watts for overclocking so that 200 watts

200 divided by 12 = 16.6A.

So why does GPU-Z say that under idle my 5850 is using roughly 11A and under 100% load it is using 41.8A

@ RetiredChief the peak output is actually 840W and continuous is 700W

So now I kind of understand how to work out the amps and that even though it says 19A on each 12V it can't actually deliever 19A on all the 12V at once

I've send Coolermaster an E-mail about me whining about the PSU whining and hopefully they will give me a refund (and not a replacement)

So what PSU's do you guys recommend, I plan on getting another 5850 in the future and overclocking it to 1000/1200 like the one i have now.

Thanks for all your help guys, really appreciate it. : )
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a c 84 B Homebuilt system
March 11, 2010 7:02:01 PM

Any 650-750W quality unit. That means ones from Antec, Corsair, Silverstone, SeaSonic, and PC Power & Cooling. The one I'm currently suggesting in that range is the Corsair 750W 80+ at $100 after rebate.
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March 11, 2010 7:45:38 PM

Yeah seems like a good price, I live in the UK though, so I can't buy from Newegg.

Would you recommend a PSU with a single Rail which has say 60amps, or a PSU that has more rails and the amerage spread across the rails?

Heres a SS of what I mean when I said that GPU-Z shows the current at 42.7A


But that seems impossible going by the equation amps = wattage divided by 12
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a b B Homebuilt system
March 11, 2010 8:25:57 PM

Not sure, I tried googling Vdoc - No results. I would egnore it as a bogus reading.

On my i5-750 OCed at 3.2 currently HWMonitor shows proccesor power @ 41.5 Watts and depending how I set it up on OC I've seen 95 Watts. I know its a bogus value and not sure how they came up with it. They would have to have a current sensor on each Phase and sum the value. There is no single point for current drawn by the CPU. If I wanted the CPU current I would have to get an adpter to consoladate the 4 positive +12 V leads to a single wire and use a o'scope with a current probe. For the GPU you would need to consoladate the + or negative leads to one and use a current probe ( it measures the magnetic field strength). Then you would have to measure the cuurens supplied thru the PCI-e bus and add that. I sligthly less accure way is to measure the power at the wall outlet w/out the graphics card installed, then measure it with the graphics card installed, The difference is the power of the GPU @ Idle. This method is even less valid at full load as How do you place a processor at full load without a GPU installed. (note: One of the things I do at work is measure inrush current for 3 PSUs connected to a satellite instrument.)
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a b B Homebuilt system
March 11, 2010 8:52:32 PM

Jack, Finally read your playtool link. Good read, although nothing earth shattering, or that I didn't know.

Have some background in Power supplies, Use to teach series regulated/shunt regulated low and high voltage Power supplies (these are the REAL power supplies). Was initial hired to work with the Engineer that designed the Power supplies in a satellite instrument (really DC-DC converters with regulated outputs). Also when I ran the electronics Department for a community I had to teach Switching PSs (what is used in Computers). Although they are not the greatest as PSs go they are small, light weight and Efficient. A good series regulated (Eout adjustable and Max current out adjustable) are BIG and Heavy and NOT very efficient. But some Audio Buffs insist on them to reduce noise.

PS answer No, he just married the wrong women - Opps I forgot rule Number one, she is NEVER wrong.
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March 11, 2010 8:58:54 PM

@jack Thanks for the link, great read and very imformative with some valid points : )

@Chief, as stated in the title of this thread im a noob at powersupply's, but I will deffinately take your word about the GPU-Z reading being bogus.

Here's my rough guess of how much wattage/amperage I'll need.

CPU at 225 watts/18.75amps
GPU's at 200watts each (400 total) /16.6amps each (33.2amps total)
1 HDD, 1 Optical drive 5x Fans, I'm guessing about 5 amps/60 watts
RAM and motherboard I really dont have a clue

I'm gonna say RAM will use 50W/4.2amps
Mobo.....uhmm.....same again?

So we have
785W total and 65.35amps

And ive decided to go with this:
http://www.scan.co.uk/Products/850W-Corsair-CMPSU-850HX...
As is provides enough amps and watts for my needs and all I hear is that its top quality
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a b B Homebuilt system
March 12, 2010 2:24:16 AM

Enjoy
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March 12, 2010 8:00:49 AM

Best answer selected by omgitzfatal.
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!