Power Supply Advise Please!

PSUs: The source of DC power for all components in the PC & often a big noise source.

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CrustyDemon_R1
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Power Supply Advise Please!

Post by CrustyDemon_R1 » Fri Feb 10, 2006 3:44 pm

I'm currently at the start of building a new high end computer. Only got the case at the moment http://www.coolermaster.com/activity/830/index.html .

My next purchase is power supply. I will be liquid cooling (still researching), will definately be SLI 7800GTX 512's. The rest of components are still in research mode.

I have read some good reviews on the PC Power and Cooling Turbo-Cool 510 SSI http://www.pccasegear.com/prod2522.htm & PC Power and Cooling Turbo-Cool 1KW http://www.pccasegear.com/prod2484.htm. I havent decided which one to get as cost is no issue (big difference between the two). I'm looking for a silent supply that will have no problems running anything high end and will last for many years & handle future PSU demanding components.

Does anyone have any comments/info about the above power supplies?
Thanks in advance.

qviri
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Post by qviri » Fri Feb 10, 2006 3:54 pm

PC&Ps are not what you're looking for if you're interested in quietness. Go with a Seasonic S12, they have 500W and 600W models.

Aris
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Post by Aris » Fri Feb 10, 2006 4:04 pm

i'd also recommend the seasonic S12 500 or 600. either one will work fine for you, so just get whichever is less expensive.

TomZ
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Post by TomZ » Fri Feb 10, 2006 4:05 pm

I say Seasonic - I have the 600W which is very quiet. It doesn't have modular cables, however. This might be a drawback for you, although it doesn't matter much to me.

Erssa
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Post by Erssa » Fri Feb 10, 2006 4:10 pm

I can picture the rig, when money isn't an issue... Go with the S12 600W.

For passive silent water cooling, how about a couple of reserator 1 plus to cool the FX-60 and those 7800GTX 512's and your 3 150gb Raptors in raid-5...

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Post by El Doug » Fri Feb 10, 2006 4:39 pm

of course its a bit silly, but ive always wanted to see the 2 video cards cooled by the Reserator+ while the CPU and northbridge (if not a passive solution) in a plain Reserator.

I think it would look wicked sick having a blue and black tower behind and to each side of the case :mrgreen:



edit: hmm - just looked at that case. youre going to need some severe modding to get that thing silent - looks like a tornado in a box

Erssa
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Post by Erssa » Fri Feb 10, 2006 4:47 pm

El Doug wrote:edit: hmm - just looked at that case. youre going to need some severe modding to get that thing silent - looks like a tornado in a box
That's what I was thinking as well first, but when money isn't an issue, you don't have to mod so much... Just passive reserators on the biggest heatsources and put the HDDs in water cooled (by reserator), damped enclosures and it is doable. Maybe 1 reserator for thecpu and the hard drives and another reserator for both of the GPUs. The case has plenty of places to attach some nexus fans for 5V cooling, for example to the side of the case to pull cool air for the chipset and mosfets.

CrustyDemon_R1
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Post by CrustyDemon_R1 » Fri Feb 10, 2006 6:15 pm

Thanks for the info guys...

I had looked at the seasonic 500/600 before from good write up. The only thing I thought they weren't SLI compatable... but after further reading i've found they are... we'll the 600 anyway. I think this is the way I'll go... Thanks again for ideas/advise... :)

The reserator 1/plus looks good as well... definately keep the noise to a minimum..... They look like the'll be on the cards as well. I'll check other passive liquid coolers as well as i think there's a few of them now.....

The case has many options to it and allows plenty of air flow.... you can put up to 9 fans or none... so options are there. Silent of course will be the least amount of fans using nexus.

Raptors will be there as well.. although a bit noisy I like the faster speeds...

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Post by qviri » Fri Feb 10, 2006 6:20 pm

CrustyDemon_R1 wrote:Raptors will be there as well.. although a bit noisy I like the faster speeds...
Actually, Raptors are agreed to be one of the quieter drives around here. You could go worse.

TomZ
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Post by TomZ » Sat Feb 11, 2006 6:44 am

I've got a pair of 74GB Raptors in a RAID configuration. They are quiet in terms of "spinning" noise (after startup), but there is a decent amount of seek noise. If you are going for a silent PC, then I think Raptors may need to be suspended or otherwise acoustically decoupled, at least in my experience.

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Post by Erssa » Sat Feb 11, 2006 3:36 pm

TomZ wrote:I've got a pair of 74GB Raptors in a RAID configuration. They are quiet in terms of "spinning" noise (after startup), but there is a decent amount of seek noise. If you are going for a silent PC, then I think Raptors may need to be suspended or otherwise acoustically decoupled, at least in my experience.
Suspension can be hard, especially if he has multiple HDDs. Luckily Raptors don't vibrate much. Since he is going for water cooling he should put them to some kind of water cooled enclosures to the HDD that will also dampen the seek noises.

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Post by TomZ » Sat Feb 11, 2006 7:19 pm

I was thinking also, my Raptors are configured for RAID1 (mirror). So I assume this means that both drives would be commanded to seek together all the time, thus approximately doubling the noise?

El Doug
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Post by El Doug » Sat Feb 11, 2006 9:57 pm

if theyre anything like fans, they will not double the noise, but only increase by about 3db

although its an increase in volume of one of the worst sounds the PC can possibly make :?

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Post by Erssa » Sun Feb 12, 2006 6:04 am

El Doug wrote:if theyre anything like fans, they will not double the noise, but only increase by about 3db

although its an increase in volume of one of the worst sounds the PC can possibly make :?
When the difference between 2 different sound levels is 0db then the increase in noise is 3db, if the difference between the two sound levels was 6db then it would add only 1db to the higher sound level.

I doubt HDDs can run at complete sync, so when they are searching there could be some noise level difference, meaning that the sound level would probably be 1-3db louder then it is compared to 1 drive seaching. However HDDs have some other indirect noises like case resonance which could change the frequency of the noise and make it subjectively louder/more annoying.

Since decibel scale isn't linear, 10db increase in sound level corresponds as doubling of percieved loudness, this is not literally the case here with TomZ. However the subjective sound quality of 2 raptors searching could be twice as bad as 1 raptor.

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Post by TomZ » Sun Feb 12, 2006 8:43 am

Regardless of whether it is 1db, 3db, etc., one might conclude that RAID1 (mirror) is bad for a silent PC. Anyone disagree with that?

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Post by NeilBlanchard » Sun Feb 12, 2006 8:56 am

Hello Tom,

In my experience, a RAID 1 array does not write the mirror copy instantaneously, so the added noise is really just that it is spread out over a longer time. With the Samsung's seek noise being as quiet as it is, the second HD adds only minimally to the overall noise of even a very quiet system.

Put it this way: a single louder HD is far worse than a second quiet HD.

student
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Post by student » Sun Feb 12, 2006 6:27 pm

How are you going to spec the rest of your system? If it is going to be top flight stuff, then the S12-600 will not provide enough power to the +12V rail/s to power your system with 2 x 7800GTX 512MB cards in SLI.

The Seasonic S12-600 can provide 36A to the +12V rails (2 x 18A).

I've calculated the current draw for some top spec components connected to this rail below:

CPU: AMD FX-60 Maximum power consumption = 110Watts = 110Watts/12volts = 9.17A peak current drawn from +12V rail

GPU: 2 x 7800GTX 512MB Max power consumption = 2 x 125WATTS= 250WATTS = 250Watts/12Volts = 20.83A peak current drawn from +12V rail.

HDD: (these also draw current from the +5V rail but only the +12V is taken into consideration):
STORAGE: 1x Hitachi 7K500 Start-Up Current Max = 2A
OS: 1x WD1500 Read/Write Current Max (likely higher for start up but the figures are not available on WD's website) = 0.47A
SCRATCH/PAGEFILES: 1x WD1500 Read/Write Current Max = 0.47A

DVD/CD DRIVES: (these also draw current from the +5V rail but only the +12V is taken into consideration):
2 x Sony DRU810A 16X DVD RW Current Max = 2 x 1.4A = 2.8A

RAM: (also draws from +5V, +3.3v; only +12V taken into consideration):
1GB PC3200 DDR RAM (Estimate taken from SPCR) Current Max = 0.5A

TOTAL PEAK CURRENT ON +12V rails = 9.17+20.83+2+0.47+0.47+2.8+0.5 = 36.24A

Adding a 1/3 safety margin to this total to:
1) allow for drops in current that occur at higher operating tempuratures
2) ensure the PSU is loaded less than 90% at any time
3) allow some head room for future upgrades and overclocking.

the current your PSU needs to be able to supply to the +12V rails becomes:

(36.24 x 0.33) + 36.24 = 47.1A

You may recall that the Seasonic S12-600 can only provide 36A to the +12V rails, so if your system is going have similar specs to the above, a Seasonic S12-600 going to be inadequate for your needs.

If you find this a bit unbelievable, you may wish to read:
http://reviews.cnet.com/4520-3118_7-6436427-1.html
AND:
http://www.bjorn3d.com/read.php?cID=862&pageID=1929

PSU's that can supply the kind of current to the +12V rail you will probably need include:

1) Thermaltake's Purepower 680W ATX 12v 2.2 Plus EPS
http://www.thermaltake.com/2005/purepow ... /w0049.htm

2) PcPowerAndCooling TURBO-COOL® 850 SSI
http://www.pcpowercooling.com/products/ ... how=T85SSI

When choosing your PSU, watch out for the small print. For instance the well regarded FSP FX700-GLN 700Watt PSU's spec sheet says it can provide 60A across 4 +12V rails.
http://www.fsp-group.com.tw/english/1_p ... &proid=462

However the notes at the bottom say:
‧+5V & +3.3V total output is 155W max.
‧+5V & +3.3V & +12V1 & +12V2 & +12V3 & +12V4 total output not exceed 680W.

which, if you do the sums means this PSU can only output a maximum of 36.25A across all 4 +12V rails, and is therefore inadequate for your needs, even though it is an honestly rated, quality 700Watt PSU.
Last edited by student on Mon Feb 13, 2006 6:42 am, edited 5 times in total.

CrustyDemon_R1
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Post by CrustyDemon_R1 » Mon Feb 13, 2006 3:04 am

Wow.... nice write up 'student'.

So far I have decided on:
Motherboard - Still undecided... Asus or DFI.
CPU - AMD - Type still undecided...maybe AM2 sock 940 when out dunno...
HD1 - Raptor 150gig.
HD2 - Raptor 74gig.
Memory - 2x2gig sticks - Corsair or OCZ.. type undecided.
Case - Coolermaster Stacker 830 as posted.
Drive 1 - DVD
Drive 2 - DVD/CD Writer
Drive 3 - Floppy
Maybe a fan controller - Still undecided.
Cooling - Liquid as silent as possible.
.......Pump: Swiftech MCP655 12V Pump
.......Rad: ThermoChill PA160
.......CPU Block: Swiftech STORM
.......Chip Block: Swiftech MCW30
.......Fan: Nexus, Noiseblocker SX1
.......GPU Block: Swiftech MCW60
.......Hose: Tygon "R-3603" (1/2 id x 3/4 od)
.......Res: Still deciding possibly in a drive bay or two.
.......Clamps: Norma Hose Clamps
This cooling system will be quite silent and produce good cooling. Still to work out quantity (pump/rad etc) and flow direction.

This leads me back to power supply. It's and interesting post 'student' wouldn't have thought the SLI card would require that much. I'm a novice with PSU and your post brings me back to my original post of requiring a high wattage quality PSU to handle what I'm looking for and for upgrades in future. The direction of computer parts seem to require more power.

Thanks to all that have posted.
Cheers.

TomZ
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Post by TomZ » Mon Feb 13, 2006 9:39 am

AMD FX-60 Maximum power consumption = 110Watts = 110Watts/12volts = 9.17A peak current drawn from +12V rail
This is probably a little on the low side, since it assumes the voltage regulators have 100% efficiency. Probably a more realistic value would be to assume 80% efficiency, thus 110W / 12V / 80% = ~11.5A.

I also didn't see any calculations for the other MB power, such as the chipset, etc.

Finally, one other precaution - many power supplies have separate +12V rails and don't allow you to exceed the maximum current specification on either one. In other words, if you need 36A, depending on your wiring, this may end up to be 16A and 20A. So if your PSU has a maximum rating of 18A on each, then you have a problem.

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Post by qviri » Mon Feb 13, 2006 9:49 am

TomZ wrote:Finally, one other precaution - many power supplies have separate +12V rails and don't allow you to exceed the maximum current specification on either one. In other words, if you need 36A, depending on your wiring, this may end up to be 16A and 20A. So if your PSU has a maximum rating of 18A on each, then you have a problem.
The thread entitled Confused about Dual 12V lines? Here's the FAQ! is a sticky in the very forum you posted this in.

CrustyDemon_R1
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Post by CrustyDemon_R1 » Mon Feb 13, 2006 12:13 pm

This result is from using the PSU calculator http://www.extreme.outervision.com/index.jsp

System Type: Dual Processor
CPU: AMD Athlon 64 FX-60 2600 MHz Toledo 1.40v
Overclocked: 136 Watts (3000 MHz, 1.45 V)

RAM: 2 Sticks DDR2 SDRAM
Video Card: SLI - 2 x nVidia GeForce 7800 GTX 512MB
SCSI HDD 10,000 rpm: 3 HDDs
CD-ROM Drive: Yes
DVD-RW/DVD+RW Drive: Yes
Floppy Drive: Yes
Sound Blaster - All Models: Yes
Sound Blaster w/ Front Bay: Yes
USB: 6 Devices
Fan Controller: Yes
Front Bay LCD Display: Yes
Fans Regular: 4 Fans 120mm;
Water Pump: Swiftech MCP 655
Motherboard, keyboard and mouse: 43 Watts

PSU Utilization: 80% (default)

Total: 726 Watts

High end PC's certainly use a lot of power.

TomZ
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Post by TomZ » Mon Feb 13, 2006 12:21 pm

Total: 726 Watts High end PC's certainly use a lot of power.
So maybe folks will stop saying that you never need a 500W+ power supply. I can't tell you how many times I've read that on the 'net.

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Post by qviri » Mon Feb 13, 2006 12:29 pm

Yes because clearly a calculator script is smarter than a bunch of reviewers who run around with multimeters, powerangels and wire clamps :roll:

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Post by Shining Arcanine » Mon Feb 13, 2006 1:05 pm

That PSU calculator gives me 226 Watts for my system's specifications. When in reality it consumes 178 Watts at load, after the AC to DC conversion. Before the AC to DC conversion, it consumes approximately 138.84 Watts, which is about 61.4% of the figure that the mentioned PSU calculator gives me. Applying this concept to the figure of 726 Watts, I get 445.764 Watts, which sounds about right for the configuration mentioned.

By the way, there is probably no motherboard that can support such a setup since this is a hybrid of a workstation, a gaming PC and a musician's PC. A workstation would have the two dual-core processors and SCSI hard drives, but integrated video and integrated sound with air cooling. A gaming PC would have the SLI setup and water cooling, but one dual core processor, SATA hard drives and only one sound card. A musician's PC would have the two sound cards, but nothing else as it would have to be so quiet that power hungry components are out of the question.

In reality, you are not going to build such a computer and I would be suprised if you found a motherboard that supports it.

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Post by SnooP » Mon Feb 13, 2006 3:27 pm

student wrote:...47A!....
Looking good except for a couple of things: hard drive and cdroms only draw that much spinning up, so hard drives become just about irrelevent after spinning up (done at computer startup, when graphics cards are idling and not drawing much power). However theres an obvious problem that your calculations show: in a dual 12V rail psu setup, you'll very likely exceed 20A max on 12V1 (everything but cpu goes off this rail), meaning psu will shut down. Best to grab a single or tripple rail psu imo to avoid this problem.

As far as that psu calculator, well just to prove it wrong again: lets grab one of those nice opteron 165s, which apparantly draw 110w according to that psu calculator. Increase the vcore to 1.55V, and frequency to 2.7ghz for a nice overclock, and apparantly the cpu uses 235W!
Last edited by SnooP on Mon Feb 13, 2006 3:34 pm, edited 1 time in total.

qviri
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Post by qviri » Mon Feb 13, 2006 3:31 pm

:roll:

El Doug
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Post by El Doug » Mon Feb 13, 2006 10:29 pm

SnooP wrote:As far as that psu calculator, well just to prove it wrong again: lets grab one of those nice opteron 165s, which apparantly draw 110w according to that psu calculator. Increase the vcore to 1.55V, and frequency to 2.7ghz for a nice overclock, and apparantly the cpu uses 235W!
Congratulations - youve discovered why it is common practice to undervolt here

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Post by SnooP » Tue Feb 14, 2006 12:18 am

well obviously, but your missing the point - that number is close to double what the actual wattage draw would be. Also given such overclocks (165 @ 2.6-2.7ghz @ 1.55V) are often achieved using the stock hsf, its obvious the number is roughly twice the actual (since stock hsf would not handle 240w without unnacceptebly high temps).

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Post by darthan » Tue Feb 14, 2006 12:53 am

Don't listen to all the people hwo are telling you you need a 700W or 800W power supply. In fact don't listen to anyone who can't back up their numbers with actual current measurements of operating PCs. The only people I've found who do that are SPCR who have shown pretty conclusively that an absolutely top end system like you want might push 400W. Maybe. More likely it will have a peak power draw around 300-350W. The TDP ratings on CPUs are abolutely meaningless in the real world. They are simply worst case scenarios designed to cover someone's ass. If you look up (for example) AMD's quick reference guide you will find that every 90nm chip between 1.8GHz and 2.4GHz has the same TDP of 67W. This is quite simply not true. A 1.8Ghz chip draws less power than a 2.4GHz chip. The numbers commonly thrown around for graphics cards by the companies that make them are also about ass-covering, not about reality.

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Post by MikeC » Tue Feb 14, 2006 1:47 am

It's clear that a 7800GTX-512 card will draw ~100W (xbit lab says 95W, link on front page today, but it's best to round off...). Almost all of this comes from the 12V 6-pin PCIe line. So... 200W from the 12V line = ~17A.

OK, add power draw of CPU, the other main 12V sucker -- 110W from the 12V line = 9.2A, Factor in losses due to motherboard VRM efficiency, as mentionede by TomZ, call it 80%, and we get ~11.5A.

CPU + dual 7800s = 28.5A on the 12V line(s) = 342W.

Let's assume for the time being that all the 12v is coming off a single line. (because it is true, more often than not, never mind what the mfg's specs say.)

Can SPCR's favorite quiet & powerful PSU, the Seasonic S12-600 handle this? The unit is rated for...

432W on 12V
180W on 5V + 3.3V
20W on the -12V and 5Vsb

But just 600W total, not 632W.

Let's say the other lines take up 128W (high based on our real-world testing but...) That leaves 432W for the 12V lines... which is convenient & plenty enough for the VGAs and CPU.

But what about other stuff? The HDDs will pull maybe 35W together on startup but drop down to around 20W or less once they're going, and not all on the 12V line. The startup burst will not cause any kind of overload ever because the graphic cards should be drawing just a fraction of their combined 200W at that point. RAM is not significant -- maybe 5-6W max. The optical drive could pull a fair amount in a game -- maybe up to 20W.

IMO, the S12-600 should handle it fine. There shoud still be about 40~50W 12V headroom -- not the biggest margin... but probably enough as I think 130W on the other lines is an overestimate; there's probably a bit of peak overload margin on the S12's 12V line.

Note -- You might recall that in the 6 varied systems tested for power, the 3.3V & 5V lines combined for no more than ~40W in any system under any load. Even add the max possible of the -12V and 5Vsb lines, and you get only 60W total.

----------

Still I can see why some experts and company spokespeople are recommending even higher power PSUs for the most powerful dual VGA gaming systems. If it was an Intel dual-core and the latest ATI1900s, their combined 12V power demand would be right up to >420W when motherboard efficiency losses are factored in. In such a system you'd want >500W on the 12V line. 550 or 600W would give you a better safety margin. Then you're really ARE looking at 700W PSUs... :roll:

[OLD GUY RANT MODE] I'm really looking forward to the power efficiency race catching on even w/gamers. Once Prescott is retired, hopefully, both Intel and AMD (but especially Intel) will take the opportunity to put their sumo wrestler processors on a diet. At the same time that vidcards are forced to go on a starvation diet. This kind of power consumption is... so wasteful & pathetic. All this so people can get a bit more convincingly addicted into playing ever more violent murder, mayhem, gratuitous sex & war games at ever faster speed. And maybe spend not just 56 hrs continuously gaming at a PC before having a fatal heart attack at the age of 25... but 36 hrs at age 19. :roll: [/OLD GUY RANT MODE]

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