GTX 260/ GTX 275 SLI

[ericvas]

What PSU will I need to power an overclock Core i7 920 PC with GTX 260/GTX275?

Calculated Power Consumption of my system in SLI was 639W according to

http://www.extreme.outervision.com/psucalculatorlite.jsp

so do I really NEED an 850W or is 750W okie?

Anybody who has Core i7 & and SLI ? pls comment

and also include whre to buy it cheapest...thanks

 

[JohnnyLucky]

The power supply calculator results are for the entire system. It is over estimated because there are an awful lot of cheap low quality psu's of questionable performance that people insist on buying.

Two GTX 260 video cards operating in SLI mode use a combined total of 380 watts and 32 amps at full load. The Tom's hardware article about video card power consumption does not list the GTX 275 but it's probably a little bit higher.

A high quality psu such as the Corsair TX750 is an excellent choice. It has a single large +12 volt rail rated at 60 amps. It will not have any problems supplying power to your system:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139006

 

[dragonsprayer]

NO!!!!!!!!!!!!!!


YOU WANT 60-80%


700/.7 = 1000W


639w is very high - you need 4-8 hard drives and 2-3 video cards for this - is this max power? or peak power

 

[dragonsprayer]

The power supply calculator results are for the entire system. It is over estimated because there are an awful lot of cheap low quality psu's of questionable performance that people insist on buying.

Two GTX 260 video cards operating in SLI mode use a combined total of 380 watts and 32 amps at full load. The Tom's hardware article about video card power consumption does not list the GTX 275 but it's probably a little bit higher.

A high quality psu such as the Corsair TX750 is an excellent choice. It has a single large +12 volt rail rated at 60 amps. It will not have any problems supplying power to your system:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139006

Calculated Power Consumption of my system in SLI was 639W according to <<--- 700W ????


639/700 IS 90% THIS IS VERY INEFFECIETN AND YOUR PSU WILL DIE WITH AGE MOST LIKLY

note your 639 is acutal cpu? or is max power? or average power?

you want max power to be 60-80%

60% is for if you are going to add a second card later
80% is the upper range for a well balanced system you are not changing

 

[ericvas]

1000W is way over budget and I have no plan of going higher in the graphics card SLI

850W = 30+% extra power according to calc
750W = 20% extra power

Anymore confirmation from users of 750W??

gladly appreciate it

 

[ericvas]

639W is a calculated power when my system is under 80-90% full load according the link..

my current system runs fine in a 550w PSU

Core i7 920 @3.8
GTX 260
6gb ddr3 1600
640gb WD Black
DVDRW


my question if i go SLI would i really need an 850W psu or 750W is good enough?

 

[JohnnyLucky]

Dragonsprayer - we just had a similar thread a few days ago with the same issue. The TX750, like other Corsair power supplies, runs in excess of 80% efficiency anywhere between 20% and 100% of it's load capacity:

http://www.corsairmemory.com/_images/charts/tx750w_efficiency.jpg

The technical review and test results at JonnyGuru.com seem to verify Corsair's claimed efficiency, even at high temperatures.

The power hog in ericvas' system are the two video cards at 380 watts and 32 amps at full load. He doesn't have much in the way of additional components and their combined total power consumption are considerably less than the two video cards.

What am I missing?

 

[ericvas]

Sorry if the question is a rehash..thanks for the replies

all my components are 1 overclock core i7..1 HDD..1 Drive..1 Cpu Cooler..1 Current Video Card ( planning to go SLI).. and the antec 300 Fans..thats all of it..

 

[JohnnyLucky]

ericvas - I just did a little hardcore gaming research. It looks like your system's maximum sustained total power consumption during gaming is going to be about 500 watts and the maximum amperage on the large +12 volt rail will be about 40 amps. That will put the TX750 right at 86% efficiency - just 1% shy of peak efficiency.

I have a lot of reference material bookmarked. I didn't know I had information about power consumption during gaming as I am not a hardcore gamer. I learn something new all the time.

 

[ericvas]

@JohnnyLucky

TX750 will meet my needs or is it cutting too close?
Done some research also and found that tx750 ideally will meet my needs but just wants confirmation from other users of corei7...Im just paranoid i guess

Found it funny that were debating over a lousy 20 bucks...hehe

 

[dragonsprayer]

Dragonsprayer - we just had a similar thread a few days ago with the same issue. The TX750, like other Corsair power supplies, runs in excess of 80% efficiency anywhere between 20% and 100% of it's load capacity:

http://www.corsairmemory.com/_images/charts/tx750w_efficiency.jpg

The technical review and test results at JonnyGuru.com seem to verify Corsair's claimed efficiency, even at high temperatures.

The power hog in ericvas' system are the two video cards at 380 watts and 32 amps at full load. He doesn't have much in the way of additional components and their combined total power consumption are considerably less than the two video cards.

What am I missing?

interesting i look into thank you!

too big is bad -- too small is woarse

rule of thumb:

you minimium or average low power useage should be 40%
you maximum should be less then 80%

60-70% works great for max power usage

too big, you be a little inefficient and spent too much
too small you end up crashing, and with time the psu will deliver less power and crash faster and "possibly" damaged stuff


single i7 chip running in the high 3ghz with a a 2 drive raid and mid level card like the 260 216 will run fine on a good 650 and 700 or 750 is great psu

if you might add more drives and second card 850-1000w is called for

you run a 4870x2 use a 850

 

[JohnnyLucky]

You pretty much answered the question yourself when you stated your current system works fine with a 550 watt power supply. All you're doing is adding a second video card for SLI. Upgrading to a high quality 750 watt psu with a large single +12 volt rail rated at 60 amps is more than enough to handle your system.

One of the recurring problems we've had is new posters thinking they need more power than they actually do. It happens quite a lot here. The matter is compounded by the fact that quite a few of the power supply calculators are recommendations for the entire system and they're overestimated. The Nvidia web site is just as bad. Their site recommends anything from an 800 watt psu all the way up to a 1200 watt psu. The Corsair web site recommends either their 750 watt, 850 watt, or 1,000 watt psu for your system and SLI.

 

[JohnnyLucky]

dragonsprayer - quick question for you - do you consider amperage to be important? I was over at newegg.com looking at specs for GTX 260 video cards. Some of the specs list system requirements which include total wattage for the entire system and amperage on the +12 volt rail(s). I find myself paying more attention to the amperage ever since Tom's Hardware published that article about actual video card power consumption.

 

[dragonsprayer]

dragonsprayer - quick question for you - do you consider amperage to be important? I was over at newegg.com looking at specs for GTX 260 video cards. Some of the specs list system requirements which include total wattage for the entire system and amperage on the +12 volt rail(s). I find myself paying more attention to the amperage ever since Tom's Hardware published that article about actual video card power consumption.

i skip all the stories of bad psu causing systems to crash! remember the psu is the heart of your system and i always suggest spending extra and shooting for 60% if you might upgrade!


of coarse amperage is important --- WHY DO I NOT TALK ABOUT IT? good psu it is all worked out!

but is the it single rail or quad rail or dual rail?
sigle rail pc power cooling 750 is eqaul to an 850 silverstone

WHY NOT USE PC POWER COOLING ALL THE TIME? anwser non modular (i use almost 100% modular psu's)

if its a single rail are they cross connected? how are they cross conntected

single rail needs less power - research it

uncrossconnected psu are a nightmare and only low end - research it

------------
amperage of each voltage rail (3v 12v etc) over lap - does this matter? yes and no - highend psu - not really
--------------------

then there is how hot it runs, how well it cools itself and how well it can over power at rated rail or given voltage

------------------------------
why do i not talk about amerage? GOOD QUESTION AND YOUR DEAD ON!

ANSWER: with high end psu's the amps are very high and insignifcant

------------
what matters?

1) the psu runs cool THIS IS THE MOST IMPORTANT OR IT WILL BE COME LESS EFFIECIENT AND THEN overheat crash or be noisy (IF A GOOD PSU. RUNS HOT, A HGH END HIGH POWER ONE, THEN SOMETHING IS WRONG OR ITS TOO SMALL)

2) SOUND - THIS IS THE MOST IMPORTANT! WHY? if i am only using the best psu's then they all have very high amperage and quad rails are crossconnected and the single rails are ....well quick butt!~


story: years and years ago -- lets say 4 or so years ago. i used a silverstone 850w zeus. these where silverstones hevy duty and they had no match at the time. we hooked up full water cooling, 8 drives, dual 1900xtx and more - never failed --

NEVER ONE SILVERSTONE FAILURE AFTER 1.5 WEEK BURN IN

antec: years and years ago - we put way too much load on antec tri rail 650 -- this psu handled sli and quad core


OLD FAITH FULLS!!!! NEVER FAILED ME: ANTEC AND Silvestone, pC power cooling


stay away from but good: ocz failures,

ok: coolmaster NO FILAURES

total junk: to mmany to list


MOST HATED: COOLMAX

BEST NOOBIES: CORSAIR < WHY I DO NOT RECOMMNED

corasir makes some nice psu's and on sale they are good deals - but some run hot - so i stay away from!




#1 thing is your psu should blow cold air -- all my psu's are bottom mounted (lian li, antec, silverstone etc) they all blow cold air! if your psu blows hot air - replace it, ebay it, rma it or what ever!

 

[ericvas]

thanks for the input..

 

[wickedsnow]

Dragonsprayer, I'm not sure where your getting your information from but, times change and PSU's become more and more efficient every year. It's not uncommon to find good quality PSU's that run at 80%-87% efficient.

Ericvas, I know you have questions and concerns about a good PSU and/or what amount of rated wattage to get. Let me tell you about my system. It might help.

Q9650 quad OCed to 4.6GHZ on liquid cooling.
4x 2gig sticks of corsair dominator ram OCed to 1200mhz
x2 velociraptors in raid 0
x2 EVGA GTX260 Core216 majorly OCed from a stock 575/1250/1000 to 750/1500/1200 in sli.
x1 thermaltake bigwater 760i liquid cooling kit.
x1 samsung 22x dvd burner
x1 asus p5n-d mobo
x2 250mm systems fans

I run all this fully overclocked with a PC&Powercooling 750watt PSU. I've had this setup almost a year now without any hic-ups.

If i can run more parts than you with a liquid cooling system and some serious OC, you can certainly run your setup on much less. With the online calculator, it says my systems takes only 589W at full load.

You can take advise from anyone you wish my friend. But I have the proof in my current gaming rig that 750W (with the right brand PSU) is good enough.

Besides the PC&Powercooling 750W is really rated at 825W

The only rule of thumb i follow is not to purchase PSU with disconnecting cables.

Lastly, the stupid belief that having a PSU that's overkill for your system will burn it out faster? That's a joke. I'm a fully certified computer engineer, and I can tell you that's not true.
Example, my last rig was a AMD x2 5200, 2 gigs of ram, 1 500gb HDD, some junker dvd burner, and a Evga 6800gt. I ran that thing on a antec 850watt for the last 6 years. And it's still running awesome!

I hope my information has been helpful.

 

[JohnnyLucky]

I kind of figured someone would post they were powering more and/or higher end components with less power. It happens all the time here. Just surprised that it took so long.

 

[wickedsnow]

Johnnylucky, I agree.

I feel bad about the misinformation users recieve nowadays about their PSU needs.

While there's no doubt that a PSU is really the heart of the system, users are never really sure if they should get modulated or non-modulated, single or multi rails, not sure on AMP requirements, and branding.

Nice profile PIC!! lol.

 

[theAnimal]

A Power Supply Calculator gives you recommended PSU size, not system power consumption.

So in this case 639W is ~650W.

 

[JohnnyLucky]

theAnimal - That is correct. It's just a recommendation for a psu. That's why I try and look for actual power consumption articles, tests, and charts. I also agree that a high quality power supply such as the Corsair TX650 with a single large +12 volt rail rated at 52 amps is sufficient. However, ericvas only listed two choices. I had a smiliar problem last night with another thread. The poster had a very limited choice and availability of psu's.

Right now the TX750 is on sale at newegg.com for $119.99 with free shipping and there's a $20.00 mail-in rebate on top of that bringing it down to $99.99.

The TX650 is $99.99 with free shipping and it also comes with a $20.00 mail in rebate bringing it down to $79.99.

That's only a $20.00 difference between the two.

 

[ericvas]

I'm just paranoid I guess..I dont want to burn out my 1k system over a wrong decision...

Ill go either with PC Power or Corsair..Cant seem to find good deals for Antec and Silverstone PSUs...

 

[skipdashu]

theAnimal - That is correct. It's just a recommendation for a psu. That's why I try and look for actual power consumption articles, tests, and charts. I also agree that a high quality power supply such as the Corsair TX650 with a single large +12 volt rail rated at 52 amps is sufficient. However, ericvas only listed two choices. I had a smiliar problem last night with another thread. The poster had a very limited choice and availability of psu's.

Right now the TX750 is on sale at newegg.com for $119.99 with free shipping and there's a $20.00 mail-in rebate on top of that bringing it down to $99.99.

The TX650 is $99.99 with free shipping and it also comes with a $20.00 mail in rebate bringing it down to $79.99.

That's only a $20.00 difference between the two.

One other thing you might consider... most 80+ certified PSUs are at their best at or just under 50% load (I think this holds true for all consumer based PC switching PSUs). One way to size a PSU is to try to get the "normal" load as close to that as possible and still have enough max wattage/current available for full load. The goal here is being to use your PC less as a space heater and to not have to make so many offerings to the electricity gods.

Since I'm usually building dedicated number crunchers that are at full load all the time this is pretty easy... take the wall plug draw wattage * an initial guess of let's say .83 then multiply that by 2 gives me a ball park wattage rating for my PSU (I generally only use 80+ certified stuff). For my Intel Qxxxx quads with a GTS-250 or older vid card (for GPU crunching) this usually ends up with me using something like a Antec EA380, EA-430 or more recently I've had real good luck with Newegg's Rosewill RG430-2. A bit of shopping and you should find any of these for under $50 shipped.

In my regular desktop (Q9550 OC'd on cheap H2O, GTX-260, 2 HDDs, 2 optical drives, TV card, 4 fans, etc, etc) the RG530-2 (80+ bronze) has done quite well for some time now and unless I boot back to Windows for some FPS action this thing also keeps the GPU at >92% and the cores >98% load 24/7. So unless somebody throws "SLI or Xfire" into the picture I generally would double check the need for anything over 600w or $80.

With the choice only between the TX650 and the 750.. I would think that not only does the TX650 cover it all but I suspect it's likely to be running more often at a higher efficiency part of the load curve than the TX750 would... adding a couple more coins to the coffer over time in addition to the initial $20 savings.

Skip

PS: You can look up the curve for about any 80+ certified PSU sold in the US HERE

 

[JohnnyLucky]

skipdashu - That's one of the sites I have bookmarked in my pc references folder. I even downloaded their database. What we are seeing lately is new power supplies that are capable of running at near peak efficiency over a much larger operating range.

EDIT - I forgot to mention that technical reviews have discovered some power supplies rated at 80% efficiency that are not very good.

 

[skipdashu]

skipdashu - That's one of the sites I have bookmarked in my pc references folder. I even downloaded their database. What we are seeing lately is new power supplies that are capable of running at near peak efficiency over a much larger operating range.

EDIT - I forgot to mention that technical reviews have discovered some power supplies rated at 80% efficiency that are not very good.

I was wondering about that... it had seemed to me that the power curves were getting flatter with more 80+ bronze certified supplies around now also! Good deal, I say.

I've also seen a couple PSUs rated in the low/mid 500w range that SURE look like their 600+w PSUs downrated to meet the 80+ (mostly likely full load) standards. Seems OK though as they then have to compete in a lower price band and we (end consumer) get a better deal.

Can ya point me to an example of a 'sub-par' 80+ certified unit... to date I've had better than average luck with them... only toasting one after a couple of years of it running in a HOT room (my infamous 'server oven') and the fan going out w/o me noticing it.

 

[JohnnyLucky]

Check out the reviews over at jonnyguru.com

A few just barely meet the 80+ standards. A few others meet the 80+ standard but have other problems.