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How many Amps do i need?

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February 11, 2011 1:54:21 PM

good morning/afternoon/evening. i partly busted my PSU a while back while trying to overclock my ATI HD 5850.
it's a crappy no-name PSU, so i'm upgrading because i want to overclock my system (in advance of the release of Crysis 2, lol. btw: yes, i'm a fanboy! go on! hate me! xD).

anyway, so my 'advance' PSU says it can deliver 18A on the 12V line. how many amps do i need to overclock my graphics card, and possibly my CPU? (i have a core i7 920)
i was thinking of upgrading to a OCZ ModXstream Pro 600W.
the AMD website doesn't say anything about the amps, it just says the 5850 can draw 105 watts at maximum load. so i don't know where to find my info now :p 

So, can anyone tell me how many amps my card will use, and if the OCZ PSU is enough for overclocking my card and my CPU with some leftover headroom? thanks in advance! :) 

More about : amps

a c 125 U Graphics card
a c 100 K Overclocking
February 11, 2011 3:23:38 PM

Personally I don't like split 12V rails. However I think it basically means it'll give 25A on the 12V going to the mobo (CPU) and then the other 12V rails (for GPU, HDD, fans) also has 25A available which should be enough.

As a comparison,
the OCZ 600W has 24A on 3.3V, 25A on 5V, and two 12V with 25A each
a Corsair 650W has 24A on 3.3V, 30A on 5V, and 52A on 12V

It's always good to compair to Corsair PSUs because they are awesome quality. But looking at it, I can say you should be totally fine with the OCZ.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
a b U Graphics card
a b K Overclocking
February 11, 2011 4:17:54 PM

Yeah, I also prefer single-rail power supplies. With split rails you actually have to keep track of which cables go to which components.

My power supply brand ranking is this:
1. SeaSonic
2. Thermaltake Toughpower XT 675/775/875 models
3. Corsair (preferably HX or AX models)
4. Other brands that are actually made by SeaSonic
...
...
...
Every other brand is down here somewhere.
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February 11, 2011 4:45:34 PM

umm, ok. i do think i want a modular PSU because i don't think i'll be using much of those cables anyway (CPU, GPU, 1HDD, 1 CD, 2 case fans), and this way i'll save much space inside my case. though how do i know what things i should connect to what outputs then? both HDD's and CD/DVD drives use 12v too right? so what uses 5v and 3.3v?

and does a modular PSU actually save you much on space? or should i just get a non-modular PSU much cheaper? :p 
edit: i'd really like a Corsair PSU, but those things are EXPENSIVE o.O.
the OCZ 650W Modular PSU = €70 ($75), and the Corsair 600W non modular PSU = €82 ($90). that's a lot of difference between 2 decent brands. i will be OC'ing, but do i really need to pay thát much?
a c 125 U Graphics card
a c 100 K Overclocking
February 11, 2011 5:22:25 PM

Modular just keeps the case tidier, there's no other real benefits. That's why I didn't spend more on the modular HX series and instead got TX (Corsair). I just tucked the extra cables inside the back cover and it looks fine.

Anyway for a single GPU that OCZ will be fine IMO. I'm not entirely sure how they split the 12V rails but I'm sure there'll be some owner's manual with it to explain the optimal way of setting it up.
February 11, 2011 5:25:23 PM

i read online that the owners manual is really lacking, just 2 pages long :( . oh well, i'll figure it out. tnx again Wolfram :) 
a b U Graphics card
February 11, 2011 5:41:34 PM

nighthawk4 said:

the AMD website doesn't say anything about the amps, it just says the 5850 can draw 105 watts at maximum load. so i don't know where to find my info now :p 

105 watts divided by 12 volts equals 8.75 amps required. :bounce: 
a c 267 U Graphics card
a c 126 K Overclocking
February 11, 2011 6:35:16 PM

The requirement is 500W and two 6 pin 75w pci-e power connectors.
http://www.amd.com/US/PRODUCTS/DESKTOP/GRAPHICS/ATI-RAD...

If a quality psu has two such connectors, then it will be able to deliver sufficient power to them.
Overclocking, as a rule does not add much, if any to your load.

OCZ is decent quality, so you should be OK.

Check out Corsair, Antec, Seasonic, PC P&C, and XFX as other top quality units.
a c 229 U Graphics card
a c 153 K Overclocking
February 11, 2011 7:26:52 PM

Could Start here:

http://support.amd.com/us/certified/power-supplies/Page...

Sizing it is easy here:

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

The review you linked says "Borderline DC quality" which would cross it off my list.

I'd stick with the perennial champs: Corsair TX650, Antec EA-650

As for the "myths" about PSU's, I think if you limit your reading to peer reviewed published articles and avoid forum posts, you'll come away not worrying about rails or 100% modular. 100% modular is a complete waste of efficiency (small as it may be) and cost. There are certain cables that you simply can not operate a PC without, think 24 pin MoBo, 8 pin EPS, 1 PCI-E, 1 Sata Power .... making these modular simply introduces a failure point, increased electrical resistance and more manufacturing costs. Hybrid modular, where all necessary cables are hybrid and only the optional ones are modular is the best of both worlds.

http://www.tomshardware.com/news/power-supplies-psu,801...

Also, advice about brands should be taken with a few pounds of salt :) . Which of the following do you think is true ?

Antec makes crappy PSU's
Antec makes good PSU's
Antec makes very good PSU's
Antec makes great PSU's

The answer .... all of the above. Manufacturer's are in business to make money ... the more they sell the more they make. Targeting a single market segment limits the number of customers you can sell to, limiting the amount of sales. So most vendors sell to multiple market segments:

Great PSU's
CP-850 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
SG-650 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
SG-850 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...

Very Good PSU's
HCG-900 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
HCP-1200 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
CP-1000 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
TP-750 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
TPQ-850 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
EA-500 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...

Good PSU's
HCP-850 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
TPQ-1200 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
EA-750 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
EA-650 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...


Crappy PSU's
NP-650 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
TPT-650 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...
TP2-550 http://www.jonnyguru.com/modules.php?name=NDReviews&op=...

So don't pick / not pick a PSU cause it says OCZ on it .... make the initial choice Vendor / Product Line and then target what ya want by reading model specific specific reviews.
February 12, 2011 11:41:01 AM

wow jack, nice post o.o

i think i'm stepping off the OCZ PSU then. a friend recommended me a Coolermaster PSU, which i'm now looking into. it's hard to get a decent 600W PSU at $80 apparently :( 

anyway, thanks for all the info lads, now i know a LOT more about PSU's :p 
a b U Graphics card
February 12, 2011 6:30:09 PM

nighthawk4 said:
wow jack, nice post o.o

i think i'm stepping off the OCZ PSU then. a friend recommended me a Coolermaster PSU, which i'm now looking into. it's hard to get a decent 600W PSU at $80 apparently :( 

anyway, thanks for all the info lads, now i know a LOT more about PSU's :p 

Be sure to check the reviews of the PSU at jonnyguru.com and others before buying! :bounce: 
Here's a good one :
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

$80.00 after rebate with free shipping! :o  :sol: 
February 12, 2011 8:52:26 PM

tnx Clark, but i'm getting the GS600 instead. it's a lot cheaper(€68,95 = ~$60), and delivers about the same performance (except for Overheat protection, and some other small stuff).

but tnx for replying anyway :p 
!