What's the lowest I can get away with?

Sleepy · Post by **Sleepy** » Mon Sep 27, 2004 4:30 pm

I'm in the market for a silent PSU, I know what I'm going to get but I was wondering what the lowest wattage I can get away with is. I'm running:

1-DVD-RW
1-CD-RW
1-120gb HDD
1-6800 GT
1-Audigy 2 ZS Gamer
1-Floppy Drive
3-case fans
1-Soltek SL-75FRN2-L w/ Barton 2500+

Also I should mention that I'm planning on getting a new mobo and chip next year so I need to get enough juice for that. Thanks!

sthayashi · Post by **sthayashi** » Mon Sep 27, 2004 4:35 pm

300W.

But the fact that you plan on getting a new motherboard and CPU throws off the balance. You're gonna have to be a little more specific than that.

Sleepy · Post by **Sleepy** » Mon Sep 27, 2004 4:38 pm

OK here goes. I'm hopefully getting an Athlon 64 3200 and a Chaintech vnf3 - 250.

SilverBeard · Post by **SilverBeard** » Mon Sep 27, 2004 4:55 pm

Sleepy wrote:OK here goes. I'm hopefully getting an Athlon 64 3200 and a Chaintech vnf3 - 250.

A64s and new video cards need lots of 12V amps. I have seen recommendations in the 20A to 24A range. Most of the quiet psus recommended here are low on the 12V range. You have to go up to the Seasonic 460W to get 25A at 12V. For my new A64 3400+ system, I chose the Tagan 480W as it has 28A on 12V and I have seen some claims that it is quieter than Seasonic - hopefully they will do a review of the Tagan here soon!

Sleepy · Post by **Sleepy** » Mon Sep 27, 2004 5:06 pm

Hmm. Hopefully my quest for quiet won't go out the window.

Here's what I'm looking at right now but I don't know if it has the right amount of 12V rails.

http://www.nexustek.nl/nx3500.htm

Stupid boy · Post by **Stupid boy** » Mon Sep 27, 2004 6:06 pm

Don't get a power supply because its fan is quiet; you can replace any power supply's fan.

Either get a power supply because it is inexpensive or because it is efficient.

I've never used a Seasonic PSU, but I have a Sparkle PSU. Sparkles are the same as Fortrons with the same model number.

I recommend a Seasonic PSU if you have money to spend and a Sparkle if you don't. Two Sparkle 300W's is about the price of one Sparkle 350W. I recommend that you get two 300W Sparkle PSU's with 120mm fans, replace the fans and zip tie them to the outside of your case. Use one PSU for the mobo and one for everything else.

I did the above except I have one 350W PSU instead of 2 300W PSU's. The fan spins extremely slowly and quietly. A Seasonic Tornado in this position would not be much quieter.

If you want to mount your power supply the standard way, get a Seasonic Tornado. I don't know much about modern video cards, so I can't say how much juice you'll need.

Sleepy · Post by **Sleepy** » Tue Sep 28, 2004 5:24 am

Sthayashi, care to comment?

Ned Slider · Post by **Ned Slider** » Tue Sep 28, 2004 9:04 am

Sleepy wrote:Hmm. Hopefully my quest for quiet won't go out the window.

Here's what I'm looking at right now but I don't know if it has the right amount of 12V rails.

http://www.nexustek.nl/nx3500.htm

The nexus only has 16A on the 12V rail and that's not going to be enough for a 6800 graphics card plus a motherboard who's CPU is fed from the 12V rail.

Check out the Enermax Noisetaker range (reviewed by MikeC here). They are quiet and being modern supplies have plenty of current on the 12V rail. I just got the Enermax noisetaker 375 and it has dual 12V rails rated at 14A and 13A, respectively. It would give you a lot more future proofing and I would recommend it.

Ned

Sleepy · Post by **Sleepy** » Tue Sep 28, 2004 9:13 am

Thanks for the reply. Is your PSU nice and quiet? Also I'll have to look into sparkle and seasonic.

Ned Slider · Post by **Ned Slider** » Tue Sep 28, 2004 9:34 am

Yes, mine is quiet - the loudest thing in that system is now my maxtor HD.

MikeC also gave it a good rating for noise in his review. Of course a lot will depend on the ambient temp but that will be pretty much the same for any supply though. Mine never ramps up the fan even with the adjustable knob set to high but my ambient temps are quite low as I leave the side panel off my case. (I'm not too concerned with ultimate noise levels in my home office, but rather that the computers are totally inaudible from other rooms when left on overnight).

IMHO you really should be looking for a supply with 24A upwards on the 12V rail. The Enermax Nosietaker range should definately be on your shortlist.

Ned

Sleepy · Post by **Sleepy** » Tue Sep 28, 2004 9:50 am

How many watts should do it you think? 325-400?

sthayashi · Post by **sthayashi** » Tue Sep 28, 2004 10:02 am

Sleepy...

The 6800GT combo w/ an A64 3200+ has such unusual power requirements that I'm not prepared to give a recommendation, especially if what others have said is true.

The two combine probably won't draw more than 200W, but if most of that power is on the 12V line (something I just learned in this thread), then your average 300W or even 350W PSU is not going to cut it, since most provide around 16A on the 12V line. A safer bet might be one of the Enermax Noisetaker PSUs which provide 2x 12V lines each with 14-15A.

EDIT: just noticed that Ned Slider said essentially the same thing.

Sleepy · Post by **Sleepy** » Tue Sep 28, 2004 10:17 am

So what you're saying is that I need more than one 12v rail, I can't just have one high rated one? Thanks again.

Ned Slider · Post by **Ned Slider** » Tue Sep 28, 2004 2:20 pm

Sleepy wrote:So what you're saying is that I need more than one 12v rail, I can't just have one high rated one? Thanks again.

No, not quite. It doesn't really matter whether it's two rails or one so long as you have sufficient power on the 12V.

The distriibution of power within modern computers is changing. Nearly all the power hungry components now use the 12V rail so that's where you need the majority of your power (the CPU used to be fed from the 5V rail). It's not a case that a good 300W supply wouldn't be sufficient, because 300W overall probably would, just that these days you need the vast majority of it at 12V.

Rather than having just one 12V rail with, say 30-40A on it, some manufacturers are splitting this into two seperated individually regulated 12V lines. They tell us this is to seperate electrically noisy components such as disk/drive motors from the delicate supply needed for the processor/GPU etc. This may be true, I don't know, but it also has other cost benefits for the manufacturer such as being able to use cheaper lower capacity components (albeit twice as many).

Check out the following link for the exact power requirements of the 6800GT. Under load, it's pulling just under 3A (35W) on the 12V rail and 55 Watts in total across all 3 rails.

http://www.xbitlabs.com/articles/video/ ... wer_3.html

Here's a little estimate of the MAX power components will draw on the 12V rail ONLY

CPU: 6A
M/board: 1A
HD: 2.5A
2xCD/DVD: 2A
6xFan: 1.5A (CPU, 3xcase and PSU fans all 12V)
6800GT: 3A

That's 16A. Throw in another HD, or a 6800Ultra instead of the GT and you're well over. Obviously your system won't be drawing this constantly, but it's at startup where problems are most likely to occur. Often a system will power on and immediately (1-2 seconds) just power down again (fans, HDs and optical drives place a large initial spinup load on the supply). In addition, it's not ideal to be running your system near or at the maximum rated output of your supply.

As I said above, I would be looking for an absolute minimum of 20A on the 12V rail and preferably 24A or above, especially if you are looking for it to cope with future upgrades.

Ned