SL12 500 or 600?

JVM · Post by **JVM** » Tue Feb 07, 2006 9:43 pm

I've read the nVidia 6600 GT needs at least 18 amps on the 12 volt rail and I'm not sure which of these PSU's would work.

500 (S12-500):

* +3.3V: 30A / +5.0V: 30A

* +3.3V & +5.5V Combined: 180W

* +12V1: 17A / +12V2: 16A

* Total: 500W

600 (S12-600):

* +3.3V: 30A / +5.0V: 30A

* +3.3V & +5.5V Combined: 180W

* +12V1: 18A / +12V2: 18A

* Total: 600W

Independent dual +12V output lines for increased safety & twice the applications.

Does the above for the 500 watt version mean it qualifies as having more than 18 amps with both 12V rails combined? Should I just go for the 600 watt version?

Elixer · Post by **Elixer** » Tue Feb 07, 2006 9:53 pm

First off, Nvidia way overstates that. Read the Power supply fundamentals in the recommended section and look at real system power draws and you'll see that many systems don't even use the 18amps * 12 volts = 216 watts that Nvidia states. This really isn't a good way to look at required power, just a way for Nvidia to keep it's ass safe. But yes, to meet Nvidia's requirements you can add the two lines together. In your case I'm almost certain that a 500W power supply or (much) less will work. Post the rest of your system specs.

burebista · Post by **burebista** » Tue Feb 07, 2006 10:45 pm

Take a look here. 48W in full-load, that means 4A from +12V and +3.3V rail.

Writer · Post by **Writer** » Tue Feb 07, 2006 11:44 pm

JVM: The S12 500 and 600 are both on nVidia's SLI certified list. The 500 should be far more than enough for a lone 6600 GT. The only difference is that the 600 can put out more power on the 12V lines, and costs a bit more.

LURKERS: It all depends on what you're putting in your system. The correct way to choose a PSU is to add up the power needs for all your components, considering which voltage rails they each draw upon. You may wish to allow a buffer to keep your PSU from operating near its peak load...or to try and get it at its peak efficiency (which varies between models)...or to keep its fan controller from ramping the voltage up.

A lot of the advice given in these forums assumes low noise as the top priority. This advice isn't always appropriate to high end systems, however.

For example, a mildly overclocked 7800 GT draws just under 100W, possibly more if overclocked a bit further. Two of those in SLI, and you have 200W on the 12V line right there. An overclocked San Diego draws more than 120W. Go dual core, and that essentially doubles (according to tests...theoretically it should only be a 30% increase, but from what I've read that isn't the case).

Seagate hard drives can take well over 15W each on startup. Add some fans, a non-PWM fan controller, some lights (if you're into that) and the 12V current draw gets higher and higher.

Most systems don't need that much power...my systems certainly don't

...but just because most systems don't, that doesn't mean that no systems do. You have to be realistic, and that means doing the math.

autoboy · Post by **autoboy** » Wed Feb 08, 2006 12:08 am

Writer, get your information straight. A 7800 GT uses 57 watts. even overclocked it is likely under 65W. Most all systems will get by with a S12 430. I run my system with an overclocked, watercooled 3500+, overclocked X850xt , and Raptor drive on a Seasonic Super Silencer 300. I believe there is 18A on the single 12V rail and I have never had problems. I don't overvolt though. I might push it if I overvolted the system.

http://www.xbitlabs.com/articles/video/ ... 006_5.html

Ackelind · Post by **Ackelind** » Wed Feb 08, 2006 4:34 am

My last system ran fine with a 6600GT, 2 SATA drives and a cooking hot prescott with a tiny SFF 250W PSU with 16A on 12V. I even had room to spare for higher-end GFX as I've seen in reviews.

You could even go with the 330W S12.

Tzupy · Post by **Tzupy** » Wed Feb 08, 2006 10:58 am

JVM, the S12-500 should be enough for a SLI 6600GT setup. For just one, the 430 should be more than enough. But why get a 6600GT now? I got mine almost a year ago, and I want to upgrade. Better wait for the 7600GT, or if you want a new gfx card now, then get a 7800GT, which has much better performance-per-watt (twice the gfx power, just 10W more).
If you really need a S12-500 or 600, I suggest to go for the 600. I suspect the 500 is binned (after testing) by Seasonic, so I'd go for the 600. If anyone has evidence that I'm wrong on this matter, please tell me, I really want to know for sure.

JVM · Post by **JVM** » Wed Feb 08, 2006 11:40 am

Tzupy wrote:JVM, the S12-500 should be enough for a SLI 6600GT setup. For just one, the 430 should be more than enough. But why get a 6600GT now? I got mine almost a year ago, and I want to upgrade. Better wait for the 7600GT, or if you want a new gfx card now, then get a 7800GT, which has much better performance-per-watt (twice the gfx power, just 10W more).
If you really need a S12-500 or 600, I suggest to go for the 600. I suspect the 500 is binned (after testing) by Seasonic, so I'd go for the 600. If anyone has evidence that I'm wrong on this matter, please tell me, I really want to know for sure.

The reason I'm going for the 6600 GT is it should be easier to cool and provide me with good video performance--I am not a hardcore gamer. My plan is to replace the stock H/S Fan with an ACS 6 Rev 2. I know that some have said the ACS has a crappy fan, but with it spinning at no more than 1500 rpm, I am willing to take the chance because I like the idea of exhausting heat outside the case, as opposed to the Zalman approach.

Writer · Post by **Writer** » Wed Feb 08, 2006 10:56 pm

autoboy wrote:Writer, get your information straight. A 7800 GT uses 57 watts. even overclocked it is likely under 65W.

Well, this is certainly embarrasing.

I just went looking for my source for those figures, and after trying for over an hour, I can't find the place where I got those figures from. I thought it was the PSU calculator at http://www.extreme.outervision.com/index.jsp but the data I thought I remembered seeing there...isn't there. I went looking through the PSU forums at Ars Technica and HardOCP, which is where I remembered finding the link originally, but couldn't find it that way either.

Please accept my sincerest apologies for any errors in my post.

I ordered a new S12 a few days ago, and I've been researching that purchase for nearly a week...reading PSU recommendations has been keeping me up late at night for a while.

If I manage to figure out where I got those figures from, I'll be sure to post a link. In the mean time, it looks like I might soon be the owner of an overpowered PSU.

Edit: Okay, I'm positive it was http://www.extreme.outervision.com/index.jsp. I distinctly remember seeing wattages listed in the dropdown lists, and next to some of the checkboxes -- for example, a "Sound Blaster w/ Front Bay" was listed as needing 18W on that page just 2 days ago. It looks like the page was edited earlier today (Feb 8th) so maybe I'm not crazy after all.

For the record, I was using an overclocked Socket 939 3700+ CPU and a 7800GT @ 470 MHz (since I have an eVGA 7800GT CO) for my figures. The 7800GT @ 470 MHz was rated at 97W. The CPU was rated around 127-131W depending on the overclock.

Tzupy · Post by **Tzupy** » Thu Feb 09, 2006 5:39 am

@JVM: your setup makes sense, but I still believe it's a bad investment to buy a 6600GT now. The 7600GT is supposed to have the same layout, so you *might* be able to use the AC Silencer on it. But the 7600GT is supposed to use higher speed memory, which would require heatsinks, which I believe the AC Silencer lacks. Hmm... Anyway, good luck!
@Writer: the xbitlabs claims of 57W for the 7800GT are to be taken as 'average consumption at 3D load'. Games in which the nVidia hardware is better used (like Doom3) make it perform better, but also draw more power. The actual power draw of a 7800GT may reach 65W under maximum possible load. And since the overclocking of the evga may add ~20%, I'd say ~78W for your card, and not 97 (maybe 97W AC draw, considering the efficiency of the PSU?).

JVM · Post by **JVM** » Thu Feb 09, 2006 9:21 am

Tzupy wrote:@JVM: your setup makes sense, but I still believe it's a bad investment to buy a 6600GT now. The 7600GT is supposed to have the same layout, so you *might* be able to use the AC Silencer on it. But the 7600GT is supposed to use higher speed memory, which would require heatsinks, which I believe the AC Silencer lacks. Hmm... Anyway, good luck!
@Writer: the xbitlabs claims of 57W for the 7800GT are to be taken as 'average consumption at 3D load'. Games in which the nVidia hardware is better used (like Doom3) make it perform better, but also draw more power. The actual power draw of a 7800GT may reach 65W under maximum possible load. And since the overclocking of the evga may add ~20%, I'd say ~78W for your card, and not 97 (maybe 97W AC draw, considering the efficiency of the PSU?).

Newegg is offering a rebate that brings down the cost of the XFX 660GT 256 MB GDDR3 version to $142 dollars.

Now, the main issue I see with using a "hotter and faster" card is the fan speed will have to be higher; thus, 1500 rpm will become at least 2000 rpm on stock ACS, which is why I didn't bother with the 6800 or 7800 series.

TomZ · Post by **TomZ** » Thu Feb 09, 2006 4:27 pm

Between the S12-500 and S12-600 is an easy choice:

If you want slightly quieter operation, go for the 600W. It is 2-4 dbA quieter on average than the 500W.

If you want to save a few bucks, go for the 500W.

I personally opted for the 600W since the cost difference was so small. It has been excellent so far.

Finally, I would try out the PSU in your system before you decide to mod it. My S12-600 is very quiet, only audible if I put my ear right up to the power supply exhaust grill. I personally don't think its worth the effort, not to mention the risk, to mod that.

JVM · Post by **JVM** » Thu Feb 09, 2006 4:32 pm

Very interesting, but where did you find the 600 watt version is 2-4db quieter on average than the 500 watt version?

TomZ · Post by **TomZ** » Thu Feb 09, 2006 4:42 pm

Very interesting, but where did you find the 600 watt version is 2-4db quieter on average than the 500 watt version?

Seasonic sent me dbA vs. load graphs for the two models.

JVM · Post by **JVM** » Thu Feb 09, 2006 5:07 pm

TomZ wrote:
Very interesting, but where did you find the 600 watt version is 2-4db quieter on average than the 500 watt version?
Seasonic sent me dbA vs. load graphs for the two models.

I read the review here and it seemed that both models were within 1 db of each other. However, I was already leaning towards the 600 watt version and your information just makes it a sweeter decision. Thanks!

Erssa · Post by **Erssa** » Sat Feb 11, 2006 3:26 pm

JVM wrote:
TomZ wrote:
Very interesting, but where did you find the 600 watt version is 2-4db quieter on average than the 500 watt version?
Seasonic sent me dbA vs. load graphs for the two models.
I read the review here and it seemed that both models were within 1 db of each other. However, I was already leaning towards the 600 watt version and your information just makes it a sweeter decision. Thanks!

Not exactly objective information. I know what the response here would have been, had he said Thermaltake send the graphs... S12-500W is supposed to be so quiet that I find this 2-4db information hard to swallow. I can bet, that on loads from 0 to 300W there will be 0db of difference and the if there is any difference in sound levels it will be on loads close to maximum when the S12 is already making around 40dbs of noise.

Seasonic has outstanding reputation, but that said I would be a bit skeptic on the graphs their marketing team has drawn... There weren't any differences in SPCR testing, so I will believe what SPCR says, until I see impartial evidence on the 2-4db claim.

TomZ: Ccould you post those graphs on this thread, so we can see ourselves what Seasonic claims?

TomZ · Post by **TomZ** » Sat Feb 11, 2006 7:17 pm

Could you post those graphs on this thread, so we can see ourselves what Seasonic claims?

I'd be happy to, but I'm not sure how. The document is a PDF. Can someone make a suggestion?

StarfishChris · Post by **StarfishChris** » Sun Feb 12, 2006 4:27 am

TomZ wrote:
Could you post those graphs on this thread, so we can see ourselves what Seasonic claims?
I'd be happy to, but I'm not sure how. The document is a PDF. Can someone make a suggestion?

Take a screenshot and upload the picture via Imageshack.