Would 600w PSU be sufficient to power 2x 8800GT in SLI?

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Pentacore

Member
Jan 10, 2008
57
1
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I read the 8800GT's use the new 65nm process so they consume less power than any of the other 8000 series cards. I've got a 600w PSU right now and am wondering if it would be enough to power 2 8800GTs. I'm using the eVGA 8800GT 512MB and would like to get a 2nd but need to know if I need to buy a new PSU.

I found a few calculators online but was wondering if there are any tools or apps that might tell me what my current draw is. Does anyone know what the exact draw of 1 8800GT is?

Thanks in advance! :)
 
P

Pentacore

Member
Jan 10, 2008
57
1
71
Q6600 B3 CPU
1 DVD drive
2 HDs
2x2 GB of RAM 667Mhz
1 Audigy soundcard

Thats it. Not sure if this helps but here are the features of my PSU:

PSU Features:

Complies with ATX12V v2.01 Version
Supports both Intel and AMD Systems
Dual 12V Rails provide independent reliable power
12V Combined output 35A
SLI Ready - Dual 6pin PCI-Express connectors
Silent 120mm Ball-bearing Blue LED Fan
Fan Speed Control Switch (low, auto, and high)
20+4 pin main connector for universal motherboard compatibility
Mesh sleeving on main cable for easier cable routing and better ventilation
Black Chrome Mirror Finish
Built-in inrush current, over temperature/current/voltage protection circuits
Safety & EMI Approval: CSA, UL, TUV, FCC


What do you think?
 
ManWithNoName

ManWithNoName

Senior member
Oct 19, 2007
396
0
0
Originally posted by: Pentacore
Q6600 B3 CPU
1 DVD drive
2 HDs
2x2 GB of RAM 667Mhz
1 Audigy soundcard

Thats it. Not sure if this helps but here are the features of my PSU:

PSU Features:

Complies with ATX12V v2.01 Version
Supports both Intel and AMD Systems
Dual 12V Rails provide independent reliable power
12V Combined output 35A
SLI Ready - Dual 6pin PCI-Express connectors
Silent 120mm Ball-bearing Blue LED Fan
Fan Speed Control Switch (low, auto, and high)
20+4 pin main connector for universal motherboard compatibility
Mesh sleeving on main cable for easier cable routing and better ventilation
Black Chrome Mirror Finish
Built-in inrush current, over temperature/current/voltage protection circuits
Safety & EMI Approval: CSA, UL, TUV, FCC


What do you think?
Click to expand...

What's the actual make and model # of your power supply? Maybe I missed it? Your wattage is fine, but quality of build is also important as is your +12v rail amperage. How did you determine the combined output? I'm only asking because a common mistake is just adding the rails together.
 
J

JackBurton

Lifer
Jul 18, 2000
15,993
14
81
Originally posted by: Pentacore
According to that calculator, I need 472watts, but JackBurton's post makes me think I'd just be cutting it too close. Its a brand new PSU, this one here to be exact, http://www.newegg.com/product/...p?item=N82E16817182032

I guess I could find use for it elsewhere. Thanks all for the help!
Click to expand...

How did you come up with 472W? I plugged your system in an got ~345W (without case fans). You already have the PSU, right? I'd just get the extra card and see how your system holds up. If you need a bigger PSU, you can always purchase it later.
 
DSF

DSF

Diamond Member
Oct 6, 2007
4,902
0
71
Originally posted by: taltamir
the suggested PSU according to eVGA is 450watt for 8800GT and GTS in SLI.
Click to expand...

Where did you find that info?
 
B

babcom

Member
Nov 25, 2004
59
1
81
For a definitive answer whether or not 600w is enough, spend around $20 and get the item here. Would be particularly useful if you build a lot.
 
T

TheVrolok

Lifer
Dec 11, 2000
24,254
4,092
136
Wow, I tried the aforementioned site to calculate and as it stands, I'm damn near my 620W limit as it is.

Q6600 @ 3.0
w\ Arctic Freezer 7 Pro
512MB 8800GT
1 SATA HDD
1 Optical Drive

2x120mm LED Fans
1x120mm Fan
2x80mm Fans
1x80mm LED Fan

4xCCFLs. (2 red and 2 UV :) )

All on a Corsair 620HX.

I can't believe I'm really using upwards of 600W under load with that. I was really thinking of getting a second 8800GT when they come down in price. Maybe I'll need a new PSU first?
 
Z

zeroburrito

Member
Dec 5, 2007
128
0
0
thats because these calculators aren't very accurate. add another 50 to that psu and thats about what it can do. 350 is generous. dell is like that also.
 
taltamir

taltamir

Lifer
Mar 21, 2004
13,576
6
76
hard drives take very very VERY little power.
The intel chips are fairly power efficient (that quad core there takes less power then an X2)
The GT is fairly power efficient.

And the 350 watt psu most likely has a beefy v12 rails and puny v3 and v5.
Keep in mind that the total wattage rating of a PSU combines all the outputs it has. but the main power draw is CPU and video card, and those eat from the v12.

Also, they might upgrade the PSU if you choose certain options.
 
Puffnstuff

Puffnstuff

Lifer
Mar 9, 2005
16,255
4,928
136
Construction quality and amperage are the most important factors when choosing a ps for your system. No you probably won't use the maximum capacity of your ps however you must meet minimum amperages on the rails in order for the system to boot and run properly. I run an 850w ps with 121 amps on the 12v rails however my system usually pulls under 310w unless I've got the cpu near 100% on all cores and then my power usages spikes upwards of 400w. You must insure that you have enough amps on your rails to keep your system supplied during peak moments. Cheap ps's are nothing but an accident waiting to happen.
 
S

s44

Diamond Member
Oct 13, 2006
9,427
16
81
Originally posted by: babcom
For a definitive answer whether or not 600w is enough, spend around $20 and get the item here. Would be particularly useful if you build a lot.
Click to expand...
The Kill-A-Watt is notoriously unreliable, particularly in catching transient loads.

Dual 12V Rails
12V Combined output 35A
Click to expand...
1. 35A is rather low for a "600W" unit. That's 420W -- more like what you'd expect from a "450W" or "500W" PSU.
2. If the thing really has two rails, it can't optimally split the load between your three main power consumers: the CPU (which will suck serious juice if you're overclocking) and the two vidcards. This may cause a problem even if your total power consumption is sufficiently low.
3. Fuhjyyu mania? (I think those Rosewill units use the infamous Fuhjjyu caps.)

In other words: It might work, but I wouldn't use it.
 
P

Pentacore

Member
Jan 10, 2008
57
1
71
Originally posted by: s44
Originally posted by: babcom
For a definitive answer whether or not 600w is enough, spend around $20 and get the item here. Would be particularly useful if you build a lot.
Click to expand...
The Kill-A-Watt is notoriously unreliable, particularly in catching transient loads.

Dual 12V Rails
12V Combined output 35A
Click to expand...
1. 35A is rather low for a "600W" unit. That's 420W -- more like what you'd expect from a "450W" or "500W" PSU.
2. If the thing really has two rails, it can't optimally split the load between your three main power consumers: the CPU (which will suck serious juice if you're overclocking) and the two vidcards. This may cause a problem even if your total power consumption is sufficiently low.
3. Fuhjyyu mania? (I think those Rosewill units use the infamous Fuhjjyu caps.)

In other words: It might work, but I wouldn't use it.
Click to expand...

Sorry to revive this old thread but I'm about to buy a 2nd 8800GT to do SLI and wanted to ask. If my PSU listed above is not powerful enough, how will I know? Will the system just shutdown? Can I do any damage by using the underpowered PSU? My idea is to just buy the 2nd 8800GT and hook it up and see how it goes. I don't want to have to buy a new PSU but I will if I have to. Thanks in advance.

Also I noticed the specs for this PSU, its output lists:

Output +3.3@30A,+5V@55A,+12V1@19A,+12V2@19A,-12V@1A,+5V SB@2.5A

So wouldn't that mean 38A (19+19) and not 35A ? And what does babcom mean by "Fuhjyyu caps?"

 
R

Raider1284

Senior member
Aug 17, 2006
809
0
0
Pentacore, you cannot just add the two rails together to make a total amount of amps. its always less then the two combined.
 
Zap

Zap

Elite Member
Oct 13, 1999
22,377
7
81
Originally posted by: KrispyKreme50
I know this is off-topic, but how does HP manage to offer a computer with quad core CPU, 2 hard drives, 2 TV tuners, 8800 GT, and 8 GB memory with a 350 watt power supply? Is it because OEM power supplies are more efficient or am I missing something here?
Click to expand...

It is because they know and can control the quality of the PSU, plus exactly what goes into the system.
 
B

beray

Member
May 30, 2008
194
0
0
Originally posted by: Pentacore
Sorry to revive this old thread but I'm about to buy a 2nd 8800GT to do SLI and wanted to ask. If my PSU listed above is not powerful enough, how will I know? Will the system just shutdown? Can I do any damage by using the underpowered PSU? My idea is to just buy the 2nd 8800GT and hook it up and see how it goes. I don't want to have to buy a new PSU but I will if I have to. Thanks in advance.

Also I noticed the specs for this PSU, its output lists:

Output +3.3@30A,+5V@55A,+12V1@19A,+12V2@19A,-12V@1A,+5V SB@2.5A

So wouldn't that mean 38A (19+19) and not 35A ? And what does babcom mean by "Fuhjyyu caps?"
Click to expand...

Get a new PSU, your Rosewill's PSU is marginal for what you wanted to do... The real reason for that is here --> http://forums.anandtech.com/me...id=84&threadid=2205092

Last but not least, you should read this thread --> http://forums.anandtech.com/me...id=84&threadid=2195709
 
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