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Proof you dont need big PSU for SLI 8800GTX

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  • SLI
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Last response: in Components
January 30, 2007 11:15:05 PM

I really hope no one has posted this for fear of being chewed out. I want to help people understand that they dont need a 1000w PSU's.

http://anandtech.com/displays/showdoc.aspx?i=2904&p=2

More about : proof dont big psu sli 8800gtx

January 30, 2007 11:26:51 PM

Agreed I'm just trying to show people that want SLI that they don't need an insane PSU ( 800W+ ). I personally use the 750 silencer from PC power and cooling for just about all the gaming rigs I build.
January 30, 2007 11:50:52 PM

Just because you can get to Cincinnati to Cleveland on half a tank of gas doesn't mean you should try. :?
Related resources
a b ) Power supply
January 31, 2007 12:13:23 AM

Wisdom and travel advice - this one has everything.
January 31, 2007 1:11:07 AM

Quote:
Just because you can get to Cincinnati to Cleveland on half a tank of gas doesn't mean you should try. :?
'

Lol hell of an analogy. I know you don't need a monster PSU to run the latest rigs, but for a tiny price premium it's nice to know there is power when you need it.
a b ) Power supply
January 31, 2007 1:31:04 AM

Shue you COULD do it....

But if you are loaded enough to get 2 8800GTX's with all the fixins, why woulden't you want to brag about your 1KW PSU??
January 31, 2007 3:51:17 PM

And just because you can buy a Ferrari doesn't mean you should.

Sure bragging rights are nice to have but it really not worth it.
January 31, 2007 10:33:32 PM

to some people they are...
January 31, 2007 11:07:38 PM

and many of those people aren't secure with their...man hood and should realize that tech changes so fast that bragging rights really don't matter.
January 31, 2007 11:19:05 PM

My PS died a week ago. All I had to replace it was my cheesy 350watt generic PS, 20 pin. Threw in the 20 to 24pin pin converter and booted up my pc. Stress tested with Orthos for 5 hours, no problems. Playing games....BIG problem. I had to remove everything, except for the bare essentials, to play. To say I was pushing it would be an under statement. I was happy when my replacement came in.
It's not something I want to do again.

E6300@3.22
Giga 965P S3
2 gigs PC6400 OCZ
X1950Pro
SB A2
Theater 550PRO PCI TV Tuner
2 optical drives
1 Seagate 250 gig SATA2
Floppy with card reader
2x 120mm fans
1x80mm fan(side case)
1x92mm fan on heat sink
2x UV Cold Cathode
Front lcd display (temps, fan controler,blabla)
February 1, 2007 1:35:37 AM

Quote:
and many of those people aren't secure with their...man hood and should realize that tech changes so fast that bragging rights really don't matter.


A PSU doesn't need to stay up with the tech. It's not like a video card and if you get a solid quality one and take care of it, it will last you a couple years. I'm not disagreeing with you, I personally think that getting a 1000W PSU in most cases is a big mistake but I DO think it would be cutting it close to SLi 8800GTX's on 50A of current... :wink:
February 1, 2007 6:07:22 AM

So what happens to your just capable PSU when the next bigger, better & power hunger video card/s come along?
Find you need/want another hard drive/s and/or something else.
New PSU....
February 1, 2007 8:31:55 AM

I like to think of PSU's as "architecture", like your case, do you really want to keep changing your case?

Same with a PSU, a good quality one, which are not running close to maximum on a regular basis will last you YEARS, as long as the build it's in lasts you, like your case does.

I don't know how far this trend of power sapping gaming will go, but i do know i won't be having to change my PSU for 3 years at least (normal PSU vagaries excepted).

Maybe it's just me, but i like to have plenty of reserve power, and that bit extra really isn't expensive anyway.
February 1, 2007 8:58:38 AM

Quote:
Maybe it's just me, but i like to have plenty of reserve power, and that bit extra really isn't expensive anyway.

I like the extra power also.
Been through a few PSU's because my system upgrades have out grown them.
Last one I bought was far more than I needed, a Thermaltake Tough Power 750W.
February 1, 2007 9:21:34 AM

I remember once upon a time a 350 watt psu was all anyone ever needed, regardless of system specs. Now it seems that a transfer to a new case, an additional hard drive, or some extra money in your pocket may warrant a bigger psu and thats not always necessary. Sometimes we substitute quality for quantity. A 500 watt Antec isn't the same as a 500 watt PCP&C even though sometimes we would like to think so. This type of thinking may indeed cause us to consider more wattage during the next build or upgrade, but also consider other things like quality and efficiency.
February 1, 2007 11:50:59 AM

Quote:
WHile Corsair may be able to run that system on there 620W PSU you won't be able to add much to the PC or OC. That system is running at it's limits and the PSU will not last very long under heavy gaming. The corsair 620W PSU offers about 50A on the combined +12v rails. It's a little less then the 52A of my minimum recomendation for such a system. I prefear to suggest a 52A to 54A PSU so there is room for OCing.


The difference between 50 and 54A is trivial at best, since these are not sustained current ratings for the MTBF. It tends to be the FETs or capacitors that go out in these scenarios, mostly implicating the heatsinks, cooling design or quality of capcitors, and a PSU rated at 50A could easily be better, or worse, or the same as one rated for 54A @ 12V, that current rating is not nearly as significant as the overal build quality and design used to arrive at the rating. In a perfect world we would assume better design and build quality on the higher rated unit, but obviously that is not the case with PC PSU.

This doesn't mean I entirely disagree, you may be quite right that it couldn't last very long outputting 50A continuously, but fortunately no gaming system is using that much continuously. Even so, it would be a bit silly to buy two high end gaming cards then try to skimp on the PSU.
February 1, 2007 1:07:23 PM

Thanks Pwnage.

To expand on what Pwnage has said.
Some people, like myself, we out and got 2 x 7900GTX's and only had a crappy PS, so, upgraded to a 700W PS... what happens, shortly after the 8800GTX comes out "must use 1KW PS..." OMG I said... this is BS, my brand new PS is useless (I was having problems with one of my 7900GTX's so was going to return them both and get a couple of 8800GTX's...)
So, If I wanted to run 2 x 8800GTX's, in would not be a problem for me (Im not overclocking as a lot of people don't, so that isn't a problem) I only have two hdds and a DVD burner so there isnt a huge load on my computer. Not everyone can upgrade a PS every time a new Video
Card comes out...

Thanks for the info Pwnage.
Those that dont agree should just say "it might get you by, but dont add to much more to your system in the future without upgrading because... blah blah blah." And we dont need 10 people saying the same thing. If you agree, you dont even need to write something (people that chase stats make me sick)
February 1, 2007 1:51:16 PM

You're a Fool, YOU DON'T NEED A 800W +, thats the whole point of this thread. I get the feeling you didn't read what others posted. As I said the 750W PC Power and Cooling that I use to power the 8800GTX in SLI has plenty of head room for OCing and expansion.
February 1, 2007 1:53:57 PM

Quote:
You're a Fool, YOU DON'T NEED A 800W +, thats the whole point of this thread. I get the feeling you didn't read what others posted. As I said the 750W PC Power and Cooling that I use to power the 8800GTX in SLI has plenty of head room for OCing and expansion.

You are not very bright Pwnage, since I was refering to nVidia BS, but I guess you prefer jumping guns without reading posts :roll:
February 1, 2007 1:58:07 PM

sorry about that i thought i hit reply for R1Master :p 
February 1, 2007 2:09:32 PM

I agreed with you and expanded on it... Christ... is the English language lost...
February 1, 2007 2:11:31 PM

Quote:
I really hope no one has posted this for fear of being chewed out. I want to help people understand that they dont need a 1000w PSU's.

http://anandtech.com/displays/showdoc.aspx?i=2904&p=2


Altohugh I never did believe an 8800GTX SLI system would ever get anywhere near 1000w, when I built one I bought a 1000w psu anyway. The many benefits of a larger PSU include increased efficiency which means less power usage, lower heat output and longer life. Especially compared to a smaller PSU operating near maximum load.

Another point is futureproofing: if you ever upgrade to hardware that needs more power you won't also need to buy a new PSU.

I never really did understand why anyone would argue for only getting the bare minimum necessary. Its not like there's a big cost-difference between a high-quality 650W psu and a 1000w psu, and in the long run buying bigger saves money.
February 1, 2007 2:40:28 PM

Quote:
My PS died a week ago. All I had to replace it was my cheesy 350watt generic PS, 20 pin. Threw in the 20 to 24pin pin converter and booted up my pc. Stress tested with Orthos for 5 hours, no problems. Playing games....BIG problem. I had to remove everything, except for the bare essentials, to play. To say I was pushing it would be an under statement. I was happy when my replacement came in.
It's not something I want to do again.

E6300@3.22
Giga 965P S3
2 gigs PC6400 OCZ
X1950Pro
SB A2
Theater 550PRO PCI TV Tuner
2 optical drives
1 Seagate 250 gig SATA2
Floppy with card reader
2x 120mm fans
1x80mm fan(side case)
1x92mm fan on heat sink
2x UV Cold Cathode
Front lcd display (temps, fan controler,blabla)



OMG imagine having to run without those cold cathodes. Did your 3dmark go down much? :lol: 
February 1, 2007 3:02:54 PM

Quote:
Just because you can get to Cincinnati to Cleveland on half a tank of gas doesn't mean you should try. :?


Post of the day for sure! :trophy: :trophy: :trophy:
February 1, 2007 10:03:02 PM

Don't make fun of my Cold Cathodes. It makes the case look so much sweeter. It brings a tear to my eye. :tongue:
February 2, 2007 1:16:25 AM

if you have a 620w PSU, is it running at 620 watts all the time? or does that just mean it's rated to handle UP TO 620 watts of demand at any time?

i have to admit i'm not too hip on the whole PSU scene

also, what's with the debate? doesn't nvidia and ATI publish the power specs for their products? I know people like anandtech have published stats on how much power a stock and overclocked processor use, sooo add them all up and throw in and extra 10-20% safety margin/ futureproof margin and we have the optimal power req's - am i 'tarded?
February 2, 2007 3:13:30 PM

No power supply will run at full load all the time. The power supply will only use up as much power as it needs. meaning that what ever your configuration the power supply will only use enough power to run that configuration, if you add a part your power usage goes up if you take one out your consumption goes down. the same is with OCing

Well its not really a debate, i meant this to be a informative post. I hate it when people come to me asking me to build them a system and them thinking they need a 800W + power supply. I have never used any thing over 800W and i dont think i ever will. The whole point being you dont need anything larger than a 750W PSU to run even the most high end systems.
February 2, 2007 4:09:57 PM

Quote:
WHile Corsair may be able to run that system on there 620W PSU you won't be able to add much to the PC or OC. That system is running at it's limits and the PSU will not last very long under heavy gaming. The corsair 620W PSU offers about 50A on the combined +12v rails. It's a little less then the 52A of my minimum recomendation for such a system. I prefear to suggest a 52A to 54A PSU so there is room for OCing.


What is going to use up the rest of the amperage? 2 8800GTX cards use 380w (give or take 5w) and I suspect those numbers are taken from the socket, not from what's pulled from the PSU. The rest of the system probably uses no more than 120 watts (most but not all on the 12v rail). That still leaves 120w of headroom.

Can you point me to a reference that proves that quality PSUs will break if they're used at 80% of their rated output? IME, PSUs rarely break, and I've used a few POS PSUs (24x7) over the years. Even if one plays a game for several hours, when the game isn't running, the PSU is barely working.

As for OCing, am I correct in assuming that OCing only eats more juice i fyou raise the voltage on components? I don't see why turning up the bus speed alone would change how much power is drawn (if I"m wrong, please fill me in. thx).
February 2, 2007 4:20:48 PM

I just bought a used Silencer 750 for the rig I am building right now. e4300 on a P5N-E SLI board which will be heavily overclocked, 8800 GTS (which will probably go SLI at sometime within the next year) 3-4 HDDs a bunch of fans and two, separate, watercooling loops. I figure the 750 can handle this load easily with some headroom.

I am moving up from a PC P&C 510 which handles an opte 165 oced to 3.0GHz on a A8N32 board, 3 HDDs two 6800GTs O/Ced and a bunch of fans. I would've stuck with it but I think the second cooling loop would've pushed it pretty hard and dual 8800GTs woud have had it at max continuous with any gaming load.

Anyways, the above is meant to show that if you spend a few extra dollars and get a high quality PSU with plenty of amps you can run a helluva lot on it safely and efficiently without stressing the unit. The 510 is rated max continuous at 510 watts and Peaks at 650 watts. I believe I could run it for a few years at 510 without it dying, it is that solid of a unit. The sweetspot on the 510 is between 250 watts and 400 watts IMHO so I moved to the 750 for the extra load I wil be installing.

BTW, JonnyGuru just did a review on that 1KW PC P&C and there are some interesting results regarding efficiency. You need to get that thing up to about 400 watts for it to start working near 80% efficiency. Below 250 watts or so you see 70% efficiency so you should be sure you are pulling 450 watts on a normal load if you plan on using one of these. Jonny's review is here:
http://www.jonnyguru.com/review_details.php?id=49
February 2, 2007 4:55:48 PM

Quote:
I agreed with you and expanded on it... Christ... is the English language lost...


Not necessarily...maybe the art of reading and understand it. :) 
February 2, 2007 5:38:26 PM

Quote:
Quote:

As for OCing, am I correct in assuming that OCing only eats more juice i fyou raise the voltage on components? I don't see why turning up the bus speed alone would change how much power is drawn (if I"m wrong, please fill me in. thx).


Thats not true, overlocking a CPU or GPU will use more power from the PSU even if you dont add vcore. Adding voltage to either one is to ensure stability and will in turn eat more power than just overclocking components without increasing vcore.

Hmm....I guess that makes some sense....engine has to work harder, so it needs more gas. Personally, I've never noticed much extra heat from OCing without more voltage, though most of the time my Ocs have been odest 25-30%.
February 2, 2007 6:21:58 PM

Quote:
Quote:

As for OCing, am I correct in assuming that OCing only eats more juice i fyou raise the voltage on components? I don't see why turning up the bus speed alone would change how much power is drawn (if I"m wrong, please fill me in. thx).


Thats not true, overlocking a CPU or GPU will use more power from the PSU even if you dont add vcore. Adding voltage to either one is to ensure stability and will in turn eat more power than just overclocking components without increasing vcore.

That's interesting. I ran my CPU on a PSU calculator and here is what I got.

100% TDP
Opteron 165 1800MHz 1.30v = 110w
Opteron 165 3006MHz 1.30v = 184w
Opteron 165 3006MHz 1.47v = 273w

I won't vouch for the accuracy of the above numbers but it does show the relation between Vcore and freq. Nice to know info Rob as I never considered increased freq means increased power draw regardless of Vcore. Thanks.
February 3, 2007 11:29:36 AM

Quote:
Quote:

As for OCing, am I correct in assuming that OCing only eats more juice i fyou raise the voltage on components? I don't see why turning up the bus speed alone would change how much power is drawn (if I"m wrong, please fill me in. thx).


Thats not true, overlocking a CPU or GPU will use more power from the PSU even if you dont add vcore. Adding voltage to either one is to ensure stability and will in turn eat more power than just overclocking components without increasing vcore.

Even if you didn't increase the CPU or GPU speed, IE- if you adjusted down the multiplier so they ran at same speed but the bus speed was higher, it will use (granted, only a little) more power.

While the CPU or GPU may use about the same, just like these parts, the chipset will use more power running at a higher bus speed, including situations when the chipset voltage was not raised (though like with CPU or GPU, raising voltage accounts for a much larger increase in current consumption than typical clock speed increases that required that voltage increase).