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What PSU for Quad-SLI 9800GX2

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September 19, 2008 12:45:16 AM

Well im going to get a new gaming rig.

The cpu its a 9950 Phenom X4 that consumes 140W
The mobo, well any one with nvidia sli ready preferibly a cheap one
2x2gb OCZ ram cas 5-6-6-18 DDR2 800
Any hardrive would fit maybe a samsung 500gb spinpoint sata

now i want to make a sli gaming rig im going to start with one video card (9800GX2) and then buy the other one

i was wondering wich PSU i should buy.
Cuz in slizone.com i dint find this one http://www.newegg.com/Product/Product.aspx?Item=N82E168...
and i think it wont work cuz most of PSU for GX2 sli are 800W and plus.

Thnx in advance

More about : psu quad sli 9800gx2

September 19, 2008 12:52:25 AM

Power consumption:
http://www.anandtech.com/video/showdoc.aspx?i=3341&p=22

9800gx2 don't actually eat up as much power as most people believe. The X2 in the name throws them off. Under load, it's only slightly more than single 4870. Downclocked cores mean less heat and higher efficiency. If the psu has good 12v rail ampage, 750w should be enough for quad sli. Ideally, you should get more though.
September 19, 2008 1:16:28 AM

why dont you go with an Intel Processor instead of an AMD. but if you already bought the AMD leave it like that. like dagger said a good 750 PSU will be enough
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September 19, 2008 1:19:14 AM

intel are a lil bit expensive same goes for intels mobos thats why i chosed AMD over intel also the 9950 isnt a bad Quad Core CPU the only real drawback i can see is the overclock capatability

also if cou can help me finding a good deal for intel CPU/mobo in any trustable site i will be willing to reconsider
September 19, 2008 1:32:00 AM

yeah dagger good combo but not for SLI i dont think the p45 can allow me to make an scalable link interface.

another question: i made this (archaic) calc
750w(PSU) - 461w(sli-GPU in load) = 289w free for CPU
289w(PSU) - 143w (CPU under stress) = 146w free for RAM, MOBO and HD
146w(PSU) - 40w(Hardrive) = 106 just for RAM and MOBO
Can 106 what be enough for 4gb RAM and a MOBO?
September 19, 2008 1:53:35 AM

panacuba said:
yeah dagger good combo but not for SLI i dont think the p45 can allow me to make an scalable link interface.

another question: i made this (archaic) calc
750w(PSU) - 461w(sli-GPU in load) = 289w free for CPU
289w(PSU) - 143w (CPU under stress) = 146w free for RAM, MOBO and HD
146w(PSU) - 40w(Hardrive) = 106 just for RAM and MOBO
Can 106 what be enough for 4gb RAM and a MOBO?


Lol, good point. I forgot. SLI boards are expensive, and don't perform as well. 650/680i are cheap, but they can have problems, especially with quad core. They're not worth the headaches. You don't want any less than 750i, which cost at least $50 more.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Yes, the power is enough. Ram and chipset themselves won't use nearly 100w. Of course, you can't expect 100% load from even the best psu. But still, 750w should be enough. Although ideally, you should get 850w just to be safe.

In the worst case, there's still psu extension.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...


September 19, 2008 2:16:09 AM

Thnx for the replies dagger :

exelent mobo now tell me if you think that a e8400 would be a good CPU also donst consume as much as the 9950 so the GPU can have more Watts.

but i wanted a quad core cuz i know its the future and games will use more cores for procesing.

Back to the topic the GPU i want is a OCed version. with cores of 675 and 2300 can that take more power from the PSU?
September 19, 2008 2:25:18 AM

panacuba said:
Thnx for the replies dagger :

exelent mobo now tell me if you think that a e8400 would be a good CPU also donst consume as much as the 9950 so the GPU can have more Watts.

but i wanted a quad core cuz i know its the future and games will use more cores for procesing.

Back to the topic the GPU i want is a OCed version. with cores of 675 and 2300 can that take more power from the PSU?


Then you should take q6600 over e8400. 95w instead of 65w at stock, which is still a lot lower than stock 9950. Even when overclocked, the 750w psu should be enough. Or you can just get 850w to be safe.
Here's a list:
http://www.newegg.com/Product/ProductList.aspx?Submit=E...
September 19, 2008 2:37:07 AM

okey wow getting a lil bit off topic, this is a pure gaming computer im not going to rip dvds, decrypt, convert videos not even opening a worpad....just for gaming; now a quad core 16600 would have better performance than a dual core e8400?, and they wont have any bottleneck trouble with one GX2?

also i can open a new topic for this but i thin that topic about q6600 vs e8400 its going to be the 182356861248th topic about that
September 19, 2008 2:41:38 AM

panacuba said:
okey wow getting a lil bit off topic, this is a pure gaming computer im not going to rip dvds, decrypt, convert videos not even opening a worpad....just for gaming; now a quad core 16600 would have better performance than a dual core e8400?, and they wont have any bottleneck trouble with one GX2?

also i can open a new topic for this but i thin that topic about q6600 vs e8400 its going to be the 182356861248th topic about that


Consider this benchmark for an idea on how higher clocked dual vs lower clocked quad perform in non-quad vs quad optimized games:
http://www.xbitlabs.com/articles/cpu/display/core2quad-...
September 19, 2008 2:52:46 AM

thnx for all the info dagger men i luv you, tell me when you wanna eb moderator or something i will vote for you thnx for teh responses, ty men im really thnaks full, i will decide later if q6600 or e8400, i will stay reading as much info i can handle in my brain
a c 276 U Graphics card
a b 4 Gaming
September 19, 2008 2:55:50 AM

Read this article and set of tests. quad vs. dual in games:
http://www.guru3d.com/article/cpu-scaling-in-games-with...
The net is that the E8400 is superior to the Q6600 in games.
They did not include FSX and supreme commander which do use multiple cores.

At the level of the E8500 or Q9450, the vga card is much more important for gaming than the cpu.
At that level, overclocking is good for bragging, but it will not net you as much increase
in FPS as a better vga card will. Today, very few games can make use of more than two cores.
Flight simulator X and supreme commander are exceptions. It is not a trivial matter to code multi threaded programs,
and game vendors will not sell too many games that require quads to run.
I don't see this changing in the next couple of years.

Net: E8500 for the increased clock speed.

The 9800GX2 needs a 6 pin connector, and a 8 pin connector. For SLI, the psu will need a total of 4. If you pick a quality psu vendor like Corsair, Seasonic, PC P&C,etc., and it has those 4 connectors, then you can be certain that it has enough amps to be able to deliver the required power to all 4 of those connectors. The other parts do not add much load in a gaming rig.
Look at a PC P&C silencer 750:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...



a c 276 U Graphics card
a b 4 Gaming
September 19, 2008 3:02:20 AM

dagger said:
Consider this benchmark for an idea on how higher clocked dual vs lower clocked quad perform in non-quad vs quad optimized games:
http://www.xbitlabs.com/articles/cpu/display/core2quad-...

In the supplied link, the tests were done a year ago, using the E6850. While the clock speed is the same, there were changes made which makes the E8400 a suprerior cpu at the same clock speed.
September 19, 2008 7:42:28 AM

Isn't Microsoft trying to make DirectX 11 make that barrier gap for game programmers not worry about the multi-threading and also multi-coring of graphics cards to utilize the system. My understanding from the Microsoft forums they say that it will be at launch date support for 16 CPU cores and 16 GPU cores, but this is at predevelopment stage. DirectX11 will make it so developers will program if it was only 1 core each, but DirectX 11 will use its new API sets to utilize all these cores. This is what first Microsoft was trying to promise on it's release of Vista. I hope Microsoft can pull this off without any bugs.
September 19, 2008 4:22:52 PM

Your are right Geo the cpu that they benchmakr site is using is kinda old compared to the e8400, also i decided to go for the dual one, now talking about the e8500 over teh e8400 version the only advantage i see is the lil more speed that the e8500 have.

about the PSU i founded exactly one with almost the same specs at a lower price http://www.newegg.com/Product/Product.aspx?Item=N82E16817339002

in my next topic i will ask about my build and if all pieces all compatble
a c 276 U Graphics card
a b 4 Gaming
September 19, 2008 4:45:32 PM

The zephyr psu is unfamiliar to me. It does not appear on this listing of psu quality : http://www.xtremesystems.org/forums/showthread.php?t=10...
That list is a bit old, so the zephyr might be ok.
The PC P&C silencer 750 IS a tier 1 unit on that list. It is also a bit cheaper, after rebate. I think you should reconsider.
September 19, 2008 4:56:37 PM

i also cheked for the zhepr in sli zone and dint apair but if it have teh sli logo means that is a lil bit trusable right?
September 19, 2008 5:30:53 PM

panacuba said:
Your are right Geo the cpu that they benchmakr site is using is kinda old compared to the e8400, also i decided to go for the dual one, now talking about the e8500 over teh e8400 version the only advantage i see is the lil more speed that the e8500 have.

about the PSU i founded exactly one with almost the same specs at a lower price http://www.newegg.com/Product/Product.aspx?Item=N82E16817339002

in my next topic i will ask about my build and if all pieces all compatble


E8400 runs identical architecture as e6850, with smaller 45nm process and sse4.1. It's on the die-shrink phase of Intel's development cycle. You have to realize that the guru3d benchmarks are only comparing stock 2.4ghz quad to 3.0ghz dual. Frankly, with that much of a clock gap, the difference of only a few fps seemed too low, other benchmarks shows it to be higher.

The xbit lab benchmark compares dual and quad when oced, at similar clocks (3.85 for dual and 3.6 for quad). That's the reason I picked it instead of newer reviews. There are hundreds of benchmarks comparing apples to oranges, but ones that show how duals stack up with quads per clock are rare. I'd have picked a newer one given the choice. It just doesn't seem to exist.
a c 276 U Graphics card
a b 4 Gaming
September 19, 2008 5:43:31 PM

The E8400 seems to be 5-10% faster than the E6850. Looking at tom's cpu charts, that seems to be the case, even for games. In addition to sse4, there must have been some other optimizations.
If you bring overclocking into it, the OC experts here can probably tell you which chip can OC higher.
At the end, though, it is not the cpu which limits FPS, but the VGA card.
I think it is generally not the number of cores that matter, but how strong the individual cores are, and a good duo can be better there.
September 19, 2008 6:02:06 PM

geofelt said:
The E8400 seems to be 5-10% faster than the E6850. Looking at tom's cpu charts, that seems to be the case, even for games. In addition to sse4, there must have been some other optimizations.
If you bring overclocking into it, the OC experts here can probably tell you which chip can OC higher.
At the end, though, it is not the cpu which limits FPS, but the VGA card.
I think it is generally not the number of cores that matter, but how strong the individual cores are, and a good duo can be better there.


You're right in that in games, cpu don't matter nearly as much as gpu. Even at a large 600mhz difference, quad is only behind duals by a few fps in non-multithreaded games. The difference is not noticable, or useful. In high multithreaded games, the gap can be large enough to determine the difference between playable and unplayabe. Anyone who played games like Supreme Commander at higher unit counts can testify to this.

It's between using a dual and have slight, almost unnoticeable advantage in most games, or using a quad, and have an advantage large enough to be useful in a small but growing number of games. With quad, you can be assured that it can handle both old non-multithreaded games and new multithreaded ones with adequate performance, and no game will be "off-limits."
a c 276 U Graphics card
a b 4 Gaming
September 19, 2008 6:10:41 PM

dagger, you have a good point here:
It's between using a dual and have slight, almost unnoticeable advantage in most games, or using a quad, and have an advantage large enough to be useful in a small but growing number of games. With quad, you can be assured that it can handle both old non-multithreaded games and new multithreaded ones with adequate performance, and no game will be "off-limits."
For the same clock, and same cpu generation there is no downside to a quad, but possibly a very real upside. The only problem is that a quad will cost more for the same clock speed.

Maybe this is a good argument to justify a new I7.
September 19, 2008 6:17:56 PM

geofelt said:
dagger, you have a good point here:
It's between using a dual and have slight, almost unnoticeable advantage in most games, or using a quad, and have an advantage large enough to be useful in a small but growing number of games. With quad, you can be assured that it can handle both old non-multithreaded games and new multithreaded ones with adequate performance, and no game will be "off-limits."
For the same clock, and same cpu generation there is no downside to a quad, but possibly a very real upside. The only problem is that a quad will cost more for the same clock speed.

Maybe this is a good argument to justify a new I7.


i7 is on the new architecture phase of development cycle, so there is the possibility of significant increase in work done per ghz. But knowing Intel, they'll probably charge sky prices for it initially. :na: 
September 19, 2008 6:30:37 PM

when i7 is planned to be launched?
September 19, 2008 6:46:40 PM

Danke,

For my luck i will buy this new rig after i sell mine at ends of this year, and in the begining fo 2009 i will buy the new rig, maybe better pieces or even the same at lower cost, cuz i think with a quad sli it should be enought GPU powa to play at least for 2 years.

Correct me if im wrong
September 19, 2008 6:51:12 PM

panacuba said:
Danke,

For my luck i will buy this new rig after i sell mine at ends of this year and in the beginign fo 2009 i will buy the new rig, maybe better pieces or even the same at lower cost cuz i think with a quad sli it should be enought GPU powa to play at lest for 2 years.

Correct me if im wrong


It depends on what you would consider "enough." Graphics move fast. It certainly won't be on top of the food chain 2 years from now.

Also, keep in mind, i7/Nehalem will be expensive at launch, as all new hardware.
September 19, 2008 6:59:30 PM

Well i dint mean top of the video cards in two years but at least i espect that it can runs 99% of games at very ulra uber high details, and for the CPU i ting the q6600 or the e8400 can be replaced faster than the GPU

question:
You think this mobo http://www.newegg.com/Product/Product.aspx?Item=N82E168... will handel 2 9800GX2? im just worried about the size of the motherboard, the case inst a problem a thermaltake armor ill do the rest
!