SLI and PSU 700 watts

[couimet1]

i recently just put a rig in together but i think i may have skimped out on the PSU and i regret it.

but i guess before i jump the gun and start feeling crappy, can anybody tell me if this power supply
" OCZ ModXStream Pro 700W Modular High Performance Power Supply"
can support a 2 way SLI of
"EVGA 01G-P3-1373-AR GeForce GTX 460 (Fermi) Superclocked EE 1GB 256-bit GDDR5"

one con i already did see with this power supply is that it is "SLI Ready" and comes with 2 pci-e connectors. the reason why i say con, is due to the fact that my 1 GPU required 2 6 pin connectors.

so what im guessing is that this psu is compable of running SLI, but only if the GPU requires less juice. what do you guys think ? should i dump this psu and get another one ?

 

[Mousemonkey]

It could well be OK, I'm using a 620w PSU to run a pair of 560's by using the two PCIe six pins and a pair of PCIe/molex adapters.

 

[couimet1]

are you sure that you're running sufficient juice on both your cards ? 620w sounds a bit low running those cards.

 

[ko888]

For a system with two GeForce GTX 460 in 2-way SLI mode a power supply with a minimum of 610 Watts or greater with a combined +12 Volt continuous current rating of 37 Amps and with at least four 6-pin PCI Express supplementary power connectors is recommended.

Meeting the minimum +12 Volt continuous current rating specification is vastly more important than meeting the power supply's wattage specification.

During HardOCP's test review's Torture Test they were able to run the OCZ ModXStream Pro 700w at approximately 80% of its rated capacity at 45°C for 8 hours and it survived. This test is meant to simulate what gaming or hardware enthusiasts might encounter when they use their systems for extended periods of time under stressful conditions such as 3D gaming or long term stability testing and benchmarking. This approximately 80% of its rated capacity happened to be drawing 37 Amps from the combined +12 Volt rails which just happens to match the minimum recommended for GeForce GTX 460 in 2-way SLI mode. It looks like you should be able to get SLI up and running.

You should be able to use 4-pin Molex to 6-pin PCI Express adapter cables to meet your graphics cards power requirements.

 

[Mousemonkey]

are you sure that you're running sufficient juice on both your cards ? 620w sounds a bit low running those cards.

I've just powered them down after a 24/7 run with both of them and the CPU @99-100%, all PSU's are not created equal which is why I've got good ones.

 

[RazberyBandit]

It won't work. The 2nd rail of an OCZ ModXstream 700 can't provide enough power for two GTX460's. A friend of mine tried it with two MSI Cyclone GTX460's and it just would not work. He popped in a Corsair TX850 and viola - SLI.

The problem lies in the design of that model PSU. While it has two 12V rails, both with equal and ample power, they are completely divided. One powers all the cables permanently attached to the PSU, the other powers all the modular cables. So, 12V1 powers the motherboard and CPU, while 12V2 powers ALL peripherals (HDD, case fans, optical drives, and GPUs req. 6-pin PCIe power). Two 460's need all 25A the 12V2 rail is capable of. As soon as you also use an HDD and optical drive, you're screwed.

You can read the 600W version's review at Hardware Secrets for a better explanation of it's design. The only difference between the 600W and the 700W is... Well, their ratings... Let's have a look:

600W 12V1 = 25A, 12V2 = 25A, Max Combined 12V = 504W

700W 12V1 = 25A, 12V2 = 25A, Max Combined 12V = 554W

So, somehow the 700W can manage to provide 50W more 12V power than the 600W via the 12V rails. Sounds a lot more like a 650W PSU then, doesn't it? Take a look at pics of their labeled specs at Newegg:

600W http://www.newegg.com/Product/ImageGallery.aspx?CurImage=17-341-017-Z02&SpinSet=17-341-017-RS&ISList=17-341-017-Z99%2c17-341-017-Z02%2c17-341-017-Z03%2c17-341-017-Z04%2c17-341-017-Z05%2c17-341-017-Z06%2c17-341-017-Z07&S7ImageFlag=1&Item=N82E16817341017&Depa=0&WaterMark=1&Description=OCZ%20ModXStream%20Pro%20600W%20Modular%20High%20Performance%20Power%20Supply%20compatible%20with%20Intel%20Sandybridge%20Core%20i3%20i5%20i7%20and%20AMD%20Phenom

700W http://www.newegg.com/Product/ImageGallery.aspx?CurImage=17-341-018-Z03&SpinSet=17-341-018-RS&ISList=17-341-018-Z99%2c17-341-018-Z02%2c17-341-018-Z03%2c17-341-018-Z04%2c17-341-018-Z05%2c17-341-018-Z06%2c17-341-018-Z07&S7ImageFlag=1&Item=N82E16817341018&Depa=0&WaterMark=1&Description=OCZ%20ModXStream%20Pro%20700W%20Modular%20High%20Performance%20Power%20Supply%20compatible%20with%20Intel%20Sandybridge%20Core%20i3%20i5%20i7%20and%20AMD%20Phenom

Almost identical...

 

[ko888]

It won't work. The 2nd rail of an OCZ ModXstream 700 can't provide enough power for two GTX460's. A friend of mine tried it with two MSI Cyclone GTX460's and it just would not work. He popped in a Corsair TX850 and viola - SLI.

The problem lies in the design of that model PSU. While it has two 12V rails, both with equal and ample power, they are completely divided. One powers all the cables permanently attached to the PSU, the other powers all the modular cables. So, 12V1 powers the motherboard and CPU, while 12V2 powers ALL peripherals (HDD, case fans, optical drives, and GPUs req. 6-pin PCIe power). Two 460's need all 25A the 12V2 rail is capable of. As soon as you also use an HDD and optical drive, you're screwed.

You can read the 600W version's review at Hardware Secrets for a better explanation of it's design. The only difference between the 600W and the 700W is... Well, their ratings... Let's have a look:

600W 12V1 = 25A, 12V2 = 25A, Max Combined 12V = 504W

700W 12V1 = 25A, 12V2 = 25A, Max Combined 12V = 554W

So, somehow the 700W can manage to provide 50W more 12V power than the 600W via the 12V rails. Sounds a lot more like a 650W PSU then, doesn't it? Take a look at pics of their labeled specs at Newegg:

600W http://www.newegg.com/Product/ImageGallery.aspx?CurImage=17-341-017-Z02&SpinSet=17-341-017-RS&ISList=17-341-017-Z99%2c17-341-017-Z02%2c17-341-017-Z03%2c17-341-017-Z04%2c17-341-017-Z05%2c17-341-017-Z06%2c17-341-017-Z07&S7ImageFlag=1&Item=N82E16817341017&Depa=0&WaterMark=1&Description=OCZ%20ModXStream%20Pro%20600W%20Modular%20High%20Performance%20Power%20Supply%20compatible%20with%20Intel%20Sandybridge%20Core%20i3%20i5%20i7%20and%20AMD%20Phenom

700W http://www.newegg.com/Product/ImageGallery.aspx?CurImage=17-341-018-Z03&SpinSet=17-341-018-RS&ISList=17-341-018-Z99%2c17-341-018-Z02%2c17-341-018-Z03%2c17-341-018-Z04%2c17-341-018-Z05%2c17-341-018-Z06%2c17-341-018-Z07&S7ImageFlag=1&Item=N82E16817341018&Depa=0&WaterMark=1&Description=OCZ%20ModXStream%20Pro%20700W%20Modular%20High%20Performance%20Power%20Supply%20compatible%20with%20Intel%20Sandybridge%20Core%20i3%20i5%20i7%20and%20AMD%20Phenom

Almost identical...

I went back and reread the +12V rail connector distribution for the OCZ ModXStream Pro Series OCZ700MXSP :

12V1 - ATX 20(4) Pin Connector and P4/AUX(EPS) Connector
12V2 - Molex, SATA, Floppy, One 6-pin PCI Express Connector and one 8-pin 6-pin PCI Express Connector

That's just stupid and a poor design.

Time to dump that piece of ...

 

[RazberyBandit]

I tend to agree. I further scorn OCZ for labeling it "SLI Ready," which is a perfect example of marketing language intended to mislead uninformed consumers into thinking it's officially nVIDIA SLI certified, when it definitely is not.

 

[Mousemonkey]

This topic has been closed by Mousemonkey