How Big Of A PSU Is Needed For A Trading Computer?

Thinking of building a box with Core i7 950 and 3x NVS 440 @ 35 w each graphic cards , the rest is standard stuff eg DVD.

What is the minimum Power supply wattage I need?

Suggested power supplies are Seasonic 520W @ $100 or 'Great Wall' 600w @ $80 - Thailand prices.

Any comments on the brands? I gather from above comments that cheapest is not worth the risk but am I overspeccing/overpaying in terms of spec + quality (rather than Thailand price)[? Alternatives?

Also on Memory looking at Giel 3x2GB 1600 triple channel - configs are 8 8 8 or 9 9 9 - is there any meaningful difference for trading not gaming between 8 and 9?
 
Quote from mokwit:

Thinking of building a box with Core i7 950 and 3x NVS 440 @ 35 w each graphic cards , the rest is standard stuff eg DVD.

What is the minimum Power supply wattage I need?

Suggested power supplies are Seasonic 520W @ $100 or 'Great Wall' 600w @ $80 - Thailand prices.

Any comments on the brands? I gather from above comments that cheapest is not worth the risk but am I overspeccing/overpaying in terms of spec + quality (rather than Thailand price)[? Alternatives?

Also on Memory looking at Giel 3x2GB 1600 triple channel - configs are 8 8 8 or 9 9 9 - is there any meaningful difference for trading not gaming between 8 and 9?
More...

I'd run your setup through an online PSU calculator and leave out graphics since you know that. Just add 105 watts for gpu's.

The difference between 8 and 9 is .125 or 12.5%.
Will you notice it? Probably not. If money is not an issue (as in same price or close to same price) the 8 is better.

Sounds like a nice box. What real estate are you going to push with it? (as in how many what size & resolution monitors)
 
Quote from mgookin:

I see 3% difference from max efficiency to the efficiency at max rated power on your charts. 85% efficiency on an AC/DC power supply unit is expected efficiency whether in a computer or otherwise.

The acoustic noise charts are meaningless.

I guess I don't understand why you're asking me to reconsider my viewpoint.
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Your viewpoint was valid about 15 years ago but, not today. Modern systems are much more dynamic when it comes to power consumption.

That being the case you're better off sizing your power supply so that you're on the left shoulder of the curve when the system is idle. That way, your peak draw stays away from the right shoulder which not only sees a degradation in efficiency but a sharp rise in fan noise.
 
Quote from mokwit:

Thinking of building a box with Core i7 950 and 3x NVS 440 @ 35 w each graphic cards , the rest is standard stuff eg DVD.

What is the minimum Power supply wattage I need?

Suggested power supplies are Seasonic 520W @ $100 or 'Great Wall' 600w @ $80 - Thailand prices.

Any comments on the brands? I gather from above comments that cheapest is not worth the risk but am I overspeccing/overpaying in terms of spec + quality (rather than Thailand price)[? Alternatives?

Also on Memory looking at Giel 3x2GB 1600 triple channel - configs are 8 8 8 or 9 9 9 - is there any meaningful difference for trading not gaming between 8 and 9?
More...

No mention of what type and how many hard discs you're using. The thing you have to consider with them, assuming you're not using SSDs, is the current spike that occurs when you first switch the system on. Idle motors in discs and fans will draw a lot of current while they're spinning up.

Second is how long you plan to keep the system. As the capacitors in a power supply age they cause the unit to not be able to deliver the same output as it could when new. Figure on losing as much as 30% of the rated output for a power supply that's a couple of years old.

IMHO, you're probably looking at an 800W unit. A good, reliable one should probably set you back around $200.
 
Thanks guys, some things I hadn't thought of/factored in.

I would actually be using a SSD with a single [platter] HDD possibly to be added later Also 3x 120mm fans.

Looks like it would be better to spend the money overspeccing in terms of wattage and maybe also brand as a cost of $100 seems to be half price!
 
Quote from jprad:

Your viewpoint was valid about 15 years ago but, not today. Modern systems are much more dynamic when it comes to power consumption.

That being the case you're better off sizing your power supply so that you're on the left shoulder of the curve when the system is idle. That way, your peak draw stays away from the right shoulder which not only sees a degradation in efficiency but a sharp rise in fan noise.
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I think we're in agreement on how to size a PSU. The issue came up from someone saying you should get no bigger of a PSU than the calculated demand because at less than full demand your efficiency will harm you. I disagreed and argued for oversizing.

Happy trading.
 
Quote from mokwit:

"... Looks like it would be better to spend the money overspeccing in terms of wattage and maybe also brand as a cost of $100 seems to be half price!
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"Overspeccing in wattage and brand"? "$100 seems half-price"? Neither is necessary. Newegg has highly rated 650W PSUs from Antec and Corsair for about $80.
 
Maybe those are not U.S. prices? I have seen most PSU prices for 600W-700W around $70-$80. Some could be bought for $40 with promotion rebates.
 
Quote from mokwit:

Thinking of building a box with Core i7 950 and 3x NVS 440 @ 35 w each graphic cards , the rest is standard stuff eg DVD.

What is the minimum Power supply wattage I need?

Suggested power supplies are Seasonic 520W @ $100 or 'Great Wall' 600w @ $80 - Thailand prices.

Any comments on the brands? I gather from above comments that cheapest is not worth the risk but am I overspeccing/overpaying in terms of spec + quality (rather than Thailand price)[? Alternatives?

Also on Memory looking at Giel 3x2GB 1600 triple channel - configs are 8 8 8 or 9 9 9 - is there any meaningful difference for trading not gaming between 8 and 9?
More...

Im running the i7 950 chip on a 550W power supply with no problems.

Go for a unit that's quiet. Pay a few extra bucks for a good unit.
 
Quote from MarketMasher:

I put a 650W Corsair into a recent build. It's plenty, even with a video card that on overclocking pulls 319W. The video card has it's own power connector for a dedicated fan, so it pulls a bit more juice when on turbo.

(The whole system pulls 319W - not the vid card alone)
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How can you tell how many watts your rig is using?
 
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