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Will an 850 watt power supply be enough?

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February 21, 2008 6:40:37 PM

I'm building a new system, and I was just wondering if a Thermaltake ToughPower 850 watt power supply would be enough to eventually SLI two 8800 GTXs or, if my budget permits, a new series 9 card when they are released. (Side note: I know this will be enough for my system now, I'm just wondering if it would be enough with another GTX.)

Intel Core 2 Duo E6750 2.66 GHz
EVGA nVidia nForce 780i motherboard
Crucial Ballistix 2 GB (2 x 1GB) DDR2 SDRAM
2 x 250 GB Western Digital HDDs
Zalman 110mm CPU fan
nVidia 8800 GTX
2 x 120 mm case fans

Like I said, I'm sure 850 watts would be enough for this, but would it be enough for another GTX in the future, and possibly another hard drive and some more RAM? (Just wondering, Thermaltake's a pretty good brand, isn't it? Do you recommend any others?) Thanks a lot.

More about : 850 watt power supply

February 21, 2008 7:03:40 PM

Yeah, that'll be more than enough.
I bought my CoolerMaster Real Power Pro 850W for the possibility of SLI'd GTXs and I run a lot more in my case than you do!
Check my sig, that's what's running on my PSU! :) 

a c 140 ) Power supply
February 21, 2008 7:14:57 PM

Seems way more than enough....

PS peek at the CPU cooler charts on Toms home page Thermalright IFX-14Scythe SY1225SL12M won and the Zalman failed the test
PS PS...those WD hard drives are early 2005 vintage....DTR is half what current drives are.
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February 21, 2008 7:35:41 PM

Thanks for the information about the fan and stuff. I'm not going with that model, though, I'm going with the CNPS9700.
February 21, 2008 11:53:33 PM

Can't go wrong with the 9700, although the 9500 would serve you just as well unless you plan on OC WAY past 3.2.
February 23, 2008 1:33:01 PM

Bad news. As it turns out, my budget might not allow an 850 watt power supply. Will a 700 or 750 watt power supply be enough to SLI two 8800 GTXs? They both have 4 12-volt rails, each with 18 amps on each rail. The GTX requires 28 amps so two cards will use 56, leaving 16 amps for everything else. Will this be enough?
a c 243 ) Power supply
February 23, 2008 1:41:48 PM

totakeke said:
Bad news. As it turns out, my budget might not allow an 850 watt power supply. Will a 700 or 750 watt power supply be enough to SLI two 8800 GTXs? They both have 4 12-volt rails, each with 18 amps on each rail. The GTX requires 28 amps so two cards will use 56, leaving 16 amps for everything else. Will this be enough?

The GTX doesn't require 26 amps (312 watts) , that's a system power recommendation, a 700 or 750 would be fine.
February 23, 2008 1:50:20 PM

totakeke said:
Bad news. As it turns out, my budget might not allow an 850 watt power supply. Will a 700 or 750 watt power supply be enough to SLI two 8800 GTXs? They both have 4 12-volt rails, each with 18 amps on each rail. The GTX requires 28 amps so two cards will use 56, leaving 16 amps for everything else. Will this be enough?


I've got a Thermaltake Toughpower 700wt and it does fine. The 700wt or 750wt will power two 8800s just fine with whyat you have listed. The 750wt model got high honors from jonnyguru, who marked it down only because it didn't look as nice as he would have liked. I could care less about its looks. I care about the performance.
February 23, 2008 3:16:04 PM

I'm not trying to push eBay, but you might find an 850 there at a good price. I sold a brand new Antec 850W TruePower Quattro there a couple of weeks ago. The high bidder got it for $122.75 + shipping.

Worth checking out.
February 23, 2008 3:42:00 PM

Zorg said:
The PC Power & Cooling Silencer 750 Quad (Black) EPS12V 750W Power Supply would handle it with some room to grow.


The PC P&C is a good PSU, though as a personal preference, I like having a modular supply so that I only use the lines I need and not having a lot of unused lines cluttering up the case. That was the main reason I went with the TT Toughpower, along with it getting a high performance rating.
February 23, 2008 5:00:27 PM

Some of the PSUs out there have really cheesy modular connectors, I prefer to just use what I need and and stuff the balance away. My case will never win the neatness award.
February 23, 2008 5:16:57 PM

I never cared much about neatness until I got a case that had a plastic side panel. Then I suddenly liked the looks of lighted stuff inside and and a clean interior, which led to the Thermaltake Toughpower. For my computer that has an old Chieftec Dragon case, a PC P&C works fine, as no one can see what lies underneath.
a b ) Power supply
February 23, 2008 5:21:48 PM

Zorg said:
eXtreme Power Supply Calculator Lite v2.5
Official XS Tiered PSU Manufacturer Brand Listing Phase III - XtremeSystems Forums

2 8800GTX 626/2000
4 SATA HDD
2 DVD +RW
100%CPU & System Load
No cap. aging
Recommended PSU size 574W.

The PC Power & Cooling Silencer 750 Quad (Black) EPS12V 750W Power Supply would handle it with some room to grow.

Agreed. Go with the PCP&C Silencer 750 Quad. That PSU is rock stable and in Tire 1 here:
http://www.xtremesystems.org/forums/showthread.php?t=10...

February 23, 2008 6:33:46 PM

I've looked at the PC Power and Cooling PSUs and they look great, they get good reviews too, but the one thing I don't really like is the single rail. Aren't multiple rails better than just one?
February 23, 2008 7:22:40 PM

totakeke said:
I've looked at the PC Power and Cooling PSUs and they look great, they get good reviews too, but the one thing I don't really like is the single rail. Aren't multiple rails better than just one?


That's really questionable. PC P&C puts out a good argument in favor of single rail PSUs, but since that's what they specialize in, their position is somewhat biased. A well built multiple rail PSU can be just as good, but it all depends on how it is designed and built.

The same thing applies to modular verses non-modular. It depends on the build quality. Basically, I'd suggest looking through the tier listings and to try not get less than a tier 2 rating. You can also check jonnyguru.com for specifics on various PSUs and their testing.
February 23, 2008 8:07:06 PM

Come on Sailer, you know that everyone is moving that way, they just lie about it. All the Corsairs and Antec Earthwatts are single rail, and that's off the top of my head. I could get you a longer list if you want. The problem is that they lie and say that they are multi rail. Additionally, they aren't really even true multi rail. 99% are single rail with over current protection on the "rails", that isn't really a multi rail anyway. A true multi rail PSU has a voltage regulator per rail.
February 23, 2008 10:02:41 PM

You're right Zorg, which is partly why I stated that the single verses multi-rail thing is questionable. Of the top lines of PSUs, its seems they are all going single rail, but they advertise themselves as multi-rail, particualrly the modular ones. The assumption, I guess, is that its less confusing to a customer if he reads that there is a given amount of wattage per line and he see different lines. So how to easily explain all this to the average person, and to then separate the single rail modular PSUs from the true multi-rail PSUs? With specs that keep changing as new stuff is made, I can't always keep up with the particulars. I find it easier to just tell people to look for a tier 2 or better PSU.

That said, the info from PC P&C's website will still be biased to the specific PSUs they make. It can't be expected that they would make their PSU one way and then say there was something better. An example is how they tell how bad 120mm and 140mm fans are, thus justifying their 80mm fan. Yet many of their competitors are using the larger fans sizes and telling how that with a larger fan, they can move more air when necessary and have a quieter fan. My own experience is that my Toughpower with a 140mm fan is so quiet I usually can't hear it at all, but the PC P&C fan has a whine that bothers my ears, and it gets worse as it heats up.

So I do stand by my statement of getting a tier 2 or better PSU and checking the reviews from jonnyguru for the particulars on given PSUs.
February 23, 2008 10:13:03 PM

I agree with tier 2 or better, if you have the cash. Tier 3 will get you by, if you don't have the dough. The claims made by PC P&C, and all the others, have to be analyzed and each person has to determine if they think they are accurate and the weight that should be applied to each claim. I think single rail is the way to go, understanding that they are a little more dangerous... a little anyway. What irritates me is these Mfgs. that lie right on the sticker of the PSU about whether they are single rail or not. I think people should be able to decide what they want and get what they bought. Soon enough all of the PSUs are going to be single rail, unless these VGAs stop sucking more and more juice. It does look like there might be a leveling off of the VGA power draw, but I'm not holding my breath for that to continue.
February 24, 2008 12:48:49 AM

So it doesn't really matter whether I go with a single or multi-rail power supply? I've heard that if I go with a multi-rail PSU I might need to do rail balancing. Do I? (I thought I had power supplies figured out but then I found about this whole rail thing lol.)
a c 143 ) Power supply
February 24, 2008 1:06:49 AM

Single vs. multi rail should not be an issue with any good quality psu. A good quality psu will deliver stable power at full load and at high ambient temperatures. Lesser units set their specs at unrealistically low temperatures. Lesser units do not apply enough of their wattage to the 12v rails where it most counts.
Stick with the tier 1 and tier 2 units from the following list: http://www.xtremesystems.org/forums/showthread.php?t=10...

If you are preparing for possibly two 8800GTX vga cards, look for a unit that has the 4 pci-e cables that you will need.
February 24, 2008 1:14:06 AM

Yes, you might have to contend with rail balancing. The Silencer 750 will do the job just fine and is a single rail.
February 24, 2008 1:22:22 AM

I don't know why I'm asking this so far in, but rails aren't just distribution of electricity, but are actual cords aren't they? Aren't different devies powered on specific different rails?
February 24, 2008 1:24:55 AM

I depends on how the Mfg. wants to make it, I don't think there are any hard fast rules. Usually the PCIe connectors are on different rails, and the rails are often marked with a different color line or tape etc.
February 24, 2008 1:25:41 AM

I don't know why you don't just get the Silencer, do you?
February 24, 2008 1:30:45 AM

Well, I know why I didn't I was just too busy looking at power supplies. I guess I never really thought about it until now. :/  Anyway, thanks for all the help then.
February 24, 2008 1:31:25 AM

Good luck.
February 24, 2008 1:44:49 AM

He be well off with the Thermaltake Toughpower 750 wt. But either that or the Silencer are both good.

I'm starting to wonder, though, if he's confusing multi-rail and modular lines. Don't know.

I really think the OP would be best off going to Jonnyguru.com and reading the tests on both the PC P&C Silencer 750wt and the Thermaltake Toughpower 750wt. Then he can decide what features he likes best and make a choice. Just to much to try to explain everything in detail here.
February 24, 2008 1:58:41 AM

He did mention the concern about the need to balance rails, so I think he's got it. They're both good PSUs with their own shortcomings.
February 26, 2008 4:07:00 PM

Remember that each 8800 GTX requires 2 PCI-e power connectors, which means if you run 2 GTX cards, you will need 4 PCI-e connectors. I believe the Thermaltake 750 Watt power supplies only have 2 power connectors. So you will probably be better off with the 850 Watt power supply, because it comes with 4 PCI-e connectors, and 4 rails. I believe the GTX instructions say that it is prefereable to connect a different rail for each power input in order to get the amperage required.

http://www.thermaltakeusa.com/product/Power/ToughPower/toughpower_index.asp
February 26, 2008 4:32:13 PM

Or just use the Silencer 750 linked earlier. It has plenty of power, 4 PCIe connectors and is single rail. So you don't have to worry about rail balancing. It's also $40-$90 cheaper, depending on which Thermaltake you are talking about.
February 26, 2008 4:49:19 PM

Zorg said:
Or just use the Silencer 750 linked earlier. It's also $40-$90 cheaper, depending on which Thermaltake you are talking about.


I find it a bit amusing that PC P&C used to be considered as being far more expensive than the usual PSUs, but now they are competitively priced. Not quite sure if the Silencers got cheaper, the others got more expensive, or maybe a little of both. A good PSU, in any case.
February 26, 2008 5:03:07 PM

The Silencer 750 is listing at $249, but it seems to be on a perpetual sale. So your right probably both. Also the Thermaltake is an 850 so more dough for 100 more watts. The point is he doesn't need the extra juice so why pay for it.
February 26, 2008 5:26:29 PM

That's for sure about the TT 850wt. And I say that while owning one for one of my computers. That one is going to get some major upgrades and be running Crossfire in late spring, but I'm not sure I'll need the 850wt even then. At least I got it on a great sale, so it actually cost less than a normal price TT 750wt.
February 26, 2008 5:40:17 PM

Free wattage, can't go wrong there.
!