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Right PSU Wattage/ Build Advice

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July 14, 2008 9:42:33 AM

Hi, Im building a computer this summer, and was just curious what size of PSU I should get.
So far my build is

Thermaltake Armor + bws6000 (purchased)

Intel Q6600 Processor

Chiltec CPU Fan

Gtx 280 or 9800GX2

XFX Nvidia 790i Ultra Motherboard

And Im deciding between which DDR3 Ram to get.
I know its expensive etc..
but i was looking at

http://www.tigerdirect.ca/applications/SearchTools/item...

Or

http://www.tigerdirect.ca/applications/SearchTools/item...

Which is better?

But Anyways my MAIN question is what wattage should I get and how do i know its appropriate ammount
Ive been told that 1000w is overkill and just to get 750 but then others have said that 750 is not enough and to get 900+ etc.. etc..
I would prefer to buy a modular power supply
and I was looking at the
OCZ 900W Modular Power supply
Will that do the trick?
Much thanks to all the help. :p 

~Admanthemadman
July 14, 2008 12:13:01 PM

To directly answer your question, no you do not need a 1000W or even a 750W PSU for that rig. A quality 600-700W unit would suffice, but it's really hard not to recommend the PC Power & Cooling Silencer 750. Best PSU in its class if you ask me.

I also suggest you reconsider your choice to go with NVIDIA. The 790i is the best NVIDIA chipset to come out in a long time, but Intel's X48 and P45 are still superior. AMD's HD4870 is pretty much the high-end GPU of choice these days as well, and would pair nicely with one of the aforementioned Intel chipsets for some future Crossfire love. We are also starting to see the first performance numbers from the 4870X2, and it looks... promising to say the least.

One more thing, DDR3 is not worth it from a price/performance perspective. 4GB of low latency DDR2-800 is still the ticket if you ask me.
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July 14, 2008 11:11:56 PM

Well I'd say it would be either one gtx 280 or two 9800gx2's
but eventually in the future when other graphic cards come down in price
i might buy another 280 and run it in sli

The price difference in ram is because im in canada, so our dollar is worth less and its more money lol.

So i dont need 100w or 750? WHAT?

Yeah I know what you mean, But I just prefer nvidia over ati, besides ive heard that their is some heat issues with the 4870
I know ddr3 doesnt seem worth it Today, but I do believe that in the future it will most likely replace ddr 2 completely
so with that said, i'd rather be ready for that to happen
nad be able to buy good ddr3 ram when it comes out.
July 14, 2008 11:17:47 PM

For ram, the second kit is better. Tighter timings.

For psu, 750w will do, but ideally you should get 850+w to leave room for possible future sli upgrade.
July 15, 2008 6:21:42 AM

admanthemadman said:

Yeah I know what you mean, But I just prefer nvidia over ati, besides ive heard that their is some heat issues with the 4870
I know ddr3 doesnt seem worth it Today, but I do believe that in the future it will most likely replace ddr 2 completely
so with that said, i'd rather be ready for that to happen
nad be able to buy good ddr3 ram when it comes out.

The 4850 had some heat problems, but thats because its a single slot cooler. The design of the ATi (and Nvidia) cards allow for alot of heating up. Either way heat shouldnt be a problem (unless you @ something ridiculace like 90C)
a c 90 B Homebuilt system
July 15, 2008 6:25:06 AM

For one GTX 280 this is what EVGA recommends:





For two 9800gx2's homerdog and dagger gave you good advice - 750watts
July 15, 2008 9:03:05 AM

Only problem with just running a 750 watt PSU is, if you decide to go SLI in the future , are you going to have enough power on the 12 V rail to power two of these beasts? It says above they recommend 40 amps for a single card.
Not many 750W PSU's with 80 amp 12V rails. From some of the 280 tests I have seen there have been some 1000W PSU's running into difficulties handling two of these cards.
I'd definitely think 1000W! Check out the reviews :-)

The Canuck
July 15, 2008 11:40:31 AM

^They recommend 40A for the entire system, there's no way in hell a single GPU could draw that much power. Don't pay wattage ratings too much attention. A quality 750W PSU like the Silencer 750 will certainly power two GTX280s in SLI whereas a **** 1000W PSU might not.
a c 90 B Homebuilt system
July 15, 2008 1:34:22 PM

random_2 said:
Only problem with just running a 750 watt PSU is, if you decide to go SLI in the future , are you going to have enough power on the 12 V rail to power two of these beasts? It says above they recommend 40 amps for a single card.
They recommend the PSU have 40amps of +12V power for the whole system.
For a dual GTX 280 a PSU with 55 amps should be enough for a high end system. The 750W PSU homerdog recommends has 60amps of +12V power.

July 15, 2008 3:05:44 PM

Is the OCZ ModXStream 900W Modular a good power supply?
it seems fairly cheap, it smodular, and what the hell the fan glows too!
should I buy that one?
July 15, 2008 3:41:20 PM

admanthemadman said:
Is the OCZ ModXStream 900W Modular a good power supply?
it seems fairly cheap, it smodular, and what the hell the fan glows too!
should I buy that one?

That's not bad, but you'd be better off with a Corsair TX750 or PC Power and Cooling Silencer 750. As I stated previously, you don't need a 900W power supply.
July 15, 2008 4:28:36 PM

I know I dont need a 900 w power supply but just Incase for futre, i really dont feel like investing in a new one anytime at all. lol.
But its not a "**** 900w" is it?
July 15, 2008 4:55:07 PM

1000watt for that is way way way overkill, a QUALITY 700-750 should do fine, like some other posters said later on the card you have (9800gtx) will shoot down in price within a short time, becuase newer cards will be coming out and you will be able to get another one of those for a good price so I would get a bit bigger psu to leave some extra juice for another card!
July 15, 2008 5:02:14 PM

I dont have acard yet
its either going to be the 9800gx2 or gtx 280
But i should get a 750?
July 15, 2008 5:17:43 PM

admanthemadman said:
I know I dont need a 900 w power supply but just Incase for futre, i really dont feel like investing in a new one anytime at all. lol.

That's fine, I just wanted to make sure you knew it wasn't necessary.
admanthemadman said:
But its not a "**** 900w" is it?

Actually it's quite nice, but it has no 8 pin PEG connectors. You need two, one for each GTX280. 6 pin to 8 pin adapters may work, but you might as well go ahead and buy a PSU that has 8 pin connectors and save yourself some hassle.
July 15, 2008 5:42:33 PM

DAMN REALLY?
I thought it was like 12 pin or something for the GPU?
So what should I get for a modular psu then?
any suggestions
It must be modular though, im really into cable management and good airflow.
and I think all the extra cables are just a head ache.
July 15, 2008 6:51:35 PM

I agree, modular is nice. The Silverstone DA800 is pricey on Newegg (as are many PSUs) but it is definitely a high quality unit that will last you for years to come.

The Antec TPQ-850 is decidedly a step down from the DA800, but is also a lot cheaper and falls under the category of "good enough." The DA800 is a real beauty though...
July 15, 2008 9:38:30 PM

well my bad....That's what happens when ya shoot your mouth off without thinking....LOL
My apologies :-)
I could have swore I read a review, where they were having some issues with not just one 1000W PSU, but a couple of them, and they ended up dumping a 1200 watt into the system.
July 15, 2008 10:48:56 PM

random_2 said:
well my bad....That's what happens when ya shoot your mouth off without thinking....LOL
My apologies :-)
I could have swore I read a review, where they were having some issues with not just one 1000W PSU, but a couple of them, and they ended up dumping a 1200 watt into the system.



You mean like how Anandtech had problems running 4850 on 1000w psu? :na: 
http://www.anandtech.com/video/showdoc.aspx?i=3338&p=5&...

Those things happen. But normally 1000w is ample room.

Newegg has a 1000w psu for $90 ar, if you don't mind the big mail in rebate. OCZ is a fairly decent brand too, if you care about brand name. :p 
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
July 15, 2008 11:01:39 PM

That's the same PSU they used in their GTX280 review, and something is clearly wrong with it. No way in hell a 1000W PSU can't power two HD4850s unless it's broken or just a total POS.
July 15, 2008 11:18:37 PM

homerdog said:
That's the same PSU they used in their GTX280 review, and something is clearly wrong with it. No way in hell a 1000W PSU can't power two HD4850s unless it's broken or just a total POS.

Nope, the "EliteXStream" is a different model, costing $210 ar. :p 
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
July 16, 2008 1:03:54 AM

Odd that Nvidia recommend nothing less than a 1000W supply for two GTX280's and nothing less than 1200W supplies for the three card configuration. They know something we don't?....lol
July 16, 2008 3:08:33 AM

dagger said:
Nope, the "EliteXStream" is a different model, costing $210 ar. :p 
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Well it's not really a big deal, but yes it was the same power supply.
Quote:
http://www.anandtech.com/video/showdoc.aspx?i=3334&p=19

We had two GeForce GTX 280s on hand and a plethora of SLI bridges, so we of course had to run them in SLI. Now remember that a single GTX 280 uses more power than a GeForce 9800 GX2, and thus two of them is going to use a lot of power. It was so much power in fact that our OCZ EliteXStream 1000W power supply wasn't enough.

Quote:
http://www.anandtech.com/video/showdoc.aspx?i=3338&p=5&...

With two 4850s paired up in CrossFire, we once again ran into issues with our power supply. Our 1000W OCZ EliteXStream wasn't always enough for the dual-GPU setup and in Call of Duty 4 our system rebooted in the middle of our test at 2560 x 1600.

Hmm, on second thought I think we have a misunderstanding. I didn't mean to imply that this was the same model you suggested.. :sol: 
random_2 said:
Odd that Nvidia recommend nothing less than a 1000W supply for two GTX280's and nothing less than 1200W supplies for the three card configuration. They know something we don't?....lol

No, they know just as well as we do that most manufacturers overrate their power supplies. Corsair and PCP&C are exceptions; they tend to underrate their PSUs, sometimes by a lot.
July 17, 2008 9:33:45 AM

Would I be able to run it on a

SILVERSTONE STRIDER Modular 750w PSU?
Please help!
July 17, 2008 2:08:57 PM

admanthemadman said:
Would I be able to run it on a

SILVERSTONE STRIDER Modular 750w PSU?
Please help!

Like the EliteXStream it doesn't have any 8 pin PEG connectors.

And I don't mind helping, but why couldn't you look this up yourself? Google is an amazing tool :whistle: 
!