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Power Supply Requirements for the new GeForce 7800 GTX in SLI

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RyanJohn2.7t

Registered
Joined
Feb 8, 2005
Soooo..... need a little help here, thought I would stop lurking and find out what everyone thinks.

I am building a PC for a friend, gonna go with the following

AMD Athlon 64 3800+ Newcastle
A8N-SLI Premium
Western Digital 74GB Raptor
BFG 7800 GTX

Thats just the really power hungry stuff.... so he wants this for gaming, gonna throw it all in one of the new Antec P180 cases. He plans on upgrading to SLI and a dual core proc later on (about 1-2 years from now).

So I am trying to find a good PSU that I can trust will work with two of those 7800GTX's and a dual core proc, so far the only thing that looks to be a definite is the PC Power & Cooling 510 SLI-PFC.

This is given the power requirements for the 7800 that are listed here.
According to that site, a PC running SLI 7800GTX's should have about 34A of 12V available at a minimum.

So... he wants to go cheaper if it is safe, looking at the Seasonic S12-600 and it appears to be a good PSU, I am just not sure how it would work out with two rails each limited to 18A. Is the system gonna use just one rail for the CPU, and the other gets split between the VC's? If so, would that work properly for SLI'd 7800's?

Thanks for any/all advice,
ryan
 
The Sparkle FSP550-60PLG is stouter than the Seasonic, and cheaper as well. If you really want to low-buck it and have 34A, the sparkle is the way to do it. It is rated at 36A, and it is certain to exceed even this figure in reality. The Seasonic should work fine also, but is much more costly.
 
Aside from PC P&C my suggestions for such a load would be the Fortron/Sparkle FSP550-60PLG, Zippy over 500w, or maybe the OCZ 520w (this one would be really stressed). I'm only comfortable recommending a large single 12v rail design at the moment for these power levels.

The Seasonic S12 600w might handle the load, but it's hard to say at the moment until the real overclocked power consumption figures of the dual core CPU's and 7800's become known.
 
id suggest any SLI ready PCP&C

on an unrealated topic, if your going that high end already why not look into a A64 2x
 
Oklahoma Wolf said:
Aside from PC P&C my suggestions for such a load would be the Fortron/Sparkle FSP550-60PLG, Zippy over 500w, or maybe the OCZ 520w (this one would be really stressed). I'm only comfortable recommending a large single 12v rail design at the moment for these power levels.

The Seasonic S12 600w might handle the load, but it's hard to say at the moment until the real overclocked power consumption figures of the dual core CPU's and 7800's become known.
oh come on you know in your heart you want to recomend this! 4x12 lines is much better than 2 :)http://www.newegg.com/Product/Product.asp?Item=N82E16817703002
lol i dont think ive even seen a pc that required it but i know ive seen a few nutz buy em.

pc p&c 510 sli and the fsp 550 are my votes also.i dont feel the ocz is upto the job is much more is added.
 
I'm actually suggesting to him to put the money into the case/power supply/MB so that he has a long upgrade path. I have been telling him to just get the cheapest S939 A64 right now (he tends to play 3D first person games, FPS and EQ, so from what I heard those aren't too CPU intensive.... EQ being worse than FPS's), but he figures he wants the 3800 right away. He also decided he wants the best card right now so he can go SLI in about a year or so when the price is down a ways.
 
RyanJohn2.7t said:
I'm actually suggesting to him to put the money into the case/power supply/MB so that he has a long upgrade path. I have been telling him to just get the cheapest S939 A64 right now (he tends to play 3D first person games, FPS and EQ, so from what I heard those aren't too CPU intensive.... EQ being worse than FPS's), but he figures he wants the 3800 right away. He also decided he wants the best card right now so he can go SLI in about a year or so when the price is down a ways.
i think thats a great plan and a good psu is an investment.
since this will be around so long im not sure about fsp's warrenty lenght but i highley suggest the pc p&c now as its 5 years.
thier custmer service is top notch and really is a big reason in the initial high cost of the psu.
 
deathstar13 said:
oh come on you know in your heart you want to recomend this! 4x12 lines is much better than 2 :)http://www.newegg.com/Product/Product.asp?Item=N82E16817703002
lol i dont think ive even seen a pc that required it but i know ive seen a few nutz buy em.

pc p&c 510 sli and the fsp 550 are my votes also.i dont feel the ocz is upto the job is much more is added.

Hehe - Zippy has a couple that will compete with and even exceed the power offered by the 850w PC P&C, but they're hard to find ;)

IMO, OCZ should drop the dual rail 600w and have either someone other than Topower supply it, or get Topower to stop focusing so much attention to the 5v rail. The single rail 600w P6 boasts a 46A 5v rail and 35A 12v - still less 12v capacity offered already at the 550w level by Fortron and 510w level by PC P&C. Over at Zippy, there's a 600w dual rail offering 20A+26A at 12v - now that's more like it for a hardcore overclocked to the moon dual core SLI rig. That's only if one prefers dual rail configuration of course - a big single rail can be more useful and cheaper at this level ;)
 
Oklahoma Wolf said:
Hehe - Zippy has a couple that will compete with and even exceed the power offered by the 850w PC P&C, but they're hard to find ;)

IMO, OCZ should drop the dual rail 600w and have either someone other than Topower supply it, or get Topower to stop focusing so much attention to the 5v rail. The single rail 600w P6 boasts a 46A 5v rail and 35A 12v - still less 12v capacity offered already at the 550w level by Fortron and 510w level by PC P&C. Over at Zippy, there's a 600w dual rail offering 20A+26A at 12v - now that's more like it for a hardcore overclocked to the moon dual core SLI rig. That's only if one prefers dual rail configuration of course - a big single rail can be more useful and cheaper at this level ;)
agreed,i remember looking at the 600wt zippy and you mentioned an issue with atx mobos iirc?
i think someone needs to make a dual 12v line 25a each and it would be perfect.i dont even fully understand why pc p&c put 4 lines on thiers as at max only 3 could be used 1xcpu 2xsli am i correct?
 
I would strongly reccomend the Dual rail for both SLI and X2. I would also be looking ath the track record on the Mobo too. The Caps and Regulation on the MOBO will be taxed to keeping the voltage steady going to the X2s cores. This issue needs to be stress as we will start seeing more video cards and hard drives killed due to the surges brought on by the CPU core(s). It's only time and progress before we start seing the same problem with Video cards knocking out drives. I would not OC Prescott or A64 without a dual rail PSU, we are alread close to the limits on voltage at OC to have a dip or surge knock out hardware and at these currents (18-35A) something might just pop littering the inside of a case full of expensive boards.
 
AlabamaCajun said:
I would strongly reccomend the Dual rail for both SLI and X2. I would also be looking ath the track record on the Mobo too. The Caps and Regulation on the MOBO will be taxed to keeping the voltage steady going to the X2s cores. This issue needs to be stress as we will start seeing more video cards and hard drives killed due to the surges brought on by the CPU core(s). It's only time and progress before we start seing the same problem with Video cards knocking out drives. I would not OC Prescott or A64 without a dual rail PSU, we are alread close to the limits on voltage at OC to have a dip or surge knock out hardware and at these currents (18-35A) something might just pop littering the inside of a case full of expensive boards.
i dont agree with your thinking very much except the part about power needs are going up.
for 1 a good solid psu with a high single 12v line will handle any current rig.
the x2 nor any amd require high amounts of power compared to the intel line but even then a so called weak on the 12v line fsp 530 can handle them fine.

also the psu is regulating the pci-e cards power and any good psu has active pcf that would stop any killing affects.
i do see the intel P D dual core being a beast to handle but i feel a good psu with a strong 12v line is preferable over a dual 12v.
even tho the mobo says it needs 2 in reality its better off sucking off of one.as the 2 individual lines are usually not built as strong on the hardware end.

when we start seeing a shift like "okwolf" said from less strong 5v line and them being added to make the 12v line stronger will dual line 12v lines be preferable.
now this is my opinions.and saying that im no expert,nor claim to be.
 
s random said:
on an unrealated topic, if your going that high end already why not look into a A64 2x

the X2's don't give any real performance increase in gaming according to anandtech
 
if you have anything running in the background they would

and can do 2x the work at the same speed, just not 2x the speed at the same work
 
deathstar13 said:
agreed,i remember looking at the 600wt zippy and you mentioned an issue with atx mobos iirc?
i think someone needs to make a dual 12v line 25a each and it would be perfect.i dont even fully understand why pc p&c put 4 lines on thiers as at max only 3 could be used 1xcpu 2xsli am i correct?

The current issue with the OCZ 600w units is that they cannot power some dual CPU rigs due to not having enough juice available for CPU power. Other than that, and a few cases of them failing, I haven't really heard much about them. I'd like to see them thoroughly tested yet, to see if the regulation problems from the 520w are there in the 600w units. The 5v on the 520w destabilizes when 12v power draw is lower than 5v draw - makes me wonder what the point to increasing 5v capacity on the 520w was, when it's not very useful in reality even for the systems that would need it.

PC P&C is probably mainly targeting the 850w to server use - I see little use for it in the average overclocker's system just now.

Edit - thought you were talking about the OCZ 600w unit. I wonder about my brain some days. Anyway, the only issue I know of with Zippy is that some DFI boards with a 5v vdimm jumper trip the PSU's protection circuitry.

AlabamaCajun said:
we are alread close to the limits on voltage at OC to have a dip or surge knock out hardware and at these currents (18-35A) something might just pop littering the inside of a case full of expensive boards

Sorry, but that's just not an issue with a well designed PSU. If it were, most of the big names in server units would have a lot of trouble selling some of theirs. Like Zippy and their 700w 45A@12v unit.
 
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RyanJohn2.7t said:
I'm actually suggesting to him to put the money into the case/power supply/MB so that he has a long upgrade path. I have been telling him to just get the cheapest S939 A64 right now (he tends to play 3D first person games, FPS and EQ, so from what I heard those aren't too CPU intensive.... EQ being worse than FPS's), but he figures he wants the 3800 right away. He also decided he wants the best card right now so he can go SLI in about a year or so when the price is down a ways.


from what i saw of the new unreal 2007 engine that game will be very CPU intensive, ontop of that physics are getting so much more complex. just my 2 cents if your investing that much (going high end CPU anyway) then get a 2x cause itll be worth it
 
My understanding is that the Unreal 3 engine would be incorporating the "PhysX technology". I assumed since his is going to be a gaming rig that he would purchase a physics accelerator when/if they become available as the producing company claims, for latter half of 2005.

http://www.ageia.com/
 
I thought I read somewhere that the 7800GTX uses less power than the 6800U, so anything in the line of powering 6800U sli will do.
btw..wow SLI 7800GTX, just awsome
 
I was thinking the same thing, why not get a venice or san diego.
 
meh... i added the newcastle to the wish list long ago when i originally set it up for him (back in early april i think) ... that's why I made sure to mention the proc type, if figured if there was a better choice, someone would point it out :) .

I think he is willing to downgrade to the A64 3000 and save money for now, I expect him to upgrade in two years or so, so I figure it's a waste for him to spend the extra 200+ for two years of the difference.
 
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