Will 300 Watts Last

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

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zokka
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Will 300 Watts Last

Post by zokka » Sat Sep 28, 2002 5:58 am

I Was Wondering I Was thinking of getting a new quiet power supply but was wonderign whever i should go with a 300 watt or a 400 watt supply

I Have

Amd Duron 700MHz *will upgrade to something around 1.5 ghz probally
256ram
sound blaster audigy platinum
geforce 4 ti420
1 7200rm hardrive

The reason I ask is i don;t really want to have to buy another powersupply a few years down the line.

P.s does anyone know places that sell quiet power supply in the uk so far i've only found 3 places selling them

Jolt
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Post by Jolt » Sat Sep 28, 2002 6:57 am

absolutely, those components won't draw more than ~100W at full load.

Take a look at the psu-reviews here at Silent PC Review. MikeC is using a Watt meter and measures the current draw of a 2Ghz P4 system with similar components and the max power usage doestn't exceed 100W by much.

zokka
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300 vs 400

Post by zokka » Sat Sep 28, 2002 12:22 pm

wow less than a 100 watts that seems low, why does the avergage computer sold usually get equipped with a 300 watt power supply? won't my components be cooler with the 400 watt supply or does it not work that way?

davidhooper
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Post by davidhooper » Sat Sep 28, 2002 1:43 pm

Hi zokka,
You can try:
www.quietpc.com (expensive, VAT not included, high shipping)
www.koolnquiet.com (cheap, mostly sells OEM stuff, low shipping)
www.theoverclockingstore.com (small selection, free shipping)

I'm sure other forum-ers will contribute others...

MikeC
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Re: 300 vs 400

Post by MikeC » Sat Sep 28, 2002 9:03 pm

zokka wrote:wow less than a 100 watts that seems low, why does the avergage computer sold usually get equipped with a 300 watt power supply? won't my components be cooler with the 400 watt supply or does it not work that way?
No, it generally doesn't work that way. While it is *possible* that the higher rated PSU at minimum *might* pull a bit more current to keep running, the difference is likely to be tiny, insignificant in a real system. The key is the efficiency factor: if they are the same on 2 PSUs, then the power draw will be same in a given system. Check this thread for more info.

The predeominance of 300W and higher rated PSUs is a testament to the power of marketing -- begun with the intro of the AMD Athlon when overrated 230-250W PSUs showed flaky behavior. Prior to that, higher power "name brand" PSUs were only for fanatics & servers.

One thing I have not pointed out clearly in my PSU reviews is that AC power draw measured by the Kill-a-Watt device does not tell you the real PSU power delivery. You have to convert this AC power draw into DC power delivered -- if the PSU efficiency is 65%, then the ~130W max AC power I have recorded translates to ~85W in DC voltage delivered by the PSU to the PC components. This is on the ref test system, which uses 2 Segate Barracuda HDD, a P4-1.6A oc'd to 2 GHz, 512 MB RAM, etc.

If all your PCI slots are full, and you use 4 HDD and a high power GF4 video card along with a 2.8GHz P4 or top speed K7, then maybe you will hit 200W. A little headroom is good to have; a "real" 300-watter would be nice for a system like that. In reality, I think a stable, good quality 200W PSU would probably be perfectly fine for most home systems.

Ralf63
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Post by Ralf63 » Fri Oct 04, 2002 8:10 am

I dont understand why you guys always insist on avoiding above 300W PSU:s. Why is that?

Its always a better idea to buy a PSU with some overcapacity. The strain on the PSU is less, and it can supply your system with more stable current at lesser noise-levels. Finally: if your system demands exactly 280W, then any modern 300+ watt PSU are gonna deliver exactly that - regardless if its a 300W, 400W or even a 500W PSU. So you dont have to worry about your monthly bills going up. The only backdraw is the higher pricetag on the PSU itself.

As for a really superquiet PSU, I can wholeheartedly recommend Antecs new Truepower line of PSU:s - starting from 330W and up. 330W is probably enough, but I have the 430W version myself. Even with a summer room-temperature of 28C degrees, and after several hours of computing, the PSU-fans never went beyond 1700 rpm. The noise generated from this PSU is comparable with a 80mm Panaflo FBA08A12L fan at 7 volt. I can tell because I have two such 7 volt Panaflos directly beneath my Truepower 430W PSU, and I cannot hear any noise-difference between them.

Antec homepage: http://www.antec-inc.com/p_truehome.html
Truepower review: http://www.envynews.com/review.php?ID=97

Ralf63
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Post by Ralf63 » Fri Oct 04, 2002 8:35 am

Jolt wrote:absolutely, those components won't draw more than ~100W at full load.

Take a look at the psu-reviews here at Silent PC Review. MikeC is using a Watt meter and measures the current draw of a 2Ghz P4 system with similar components and the max power usage doestn't exceed 100W by much.
Both AMD:s and INTEL:s modern processors can easily demand 65-70W by themselves (standard non-overclocked settings). Add to this the motherboard; the graphic-card, the memory-units, the PCI-cards and all the CD-drives. All can easily add up way beyond 250+ W. Processor Electrical Specifications: http://users.erols.com/chare/elec.htm

MikeC
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Post by MikeC » Fri Oct 04, 2002 9:45 am

Ralf63 wrote:I dont understand why you guys always insist on avoiding above 300W PSU:s. Why is that?
Who is insisting that?

The original question here was: 300w or 400w for a modest 1.5GHz system? The answer was, why pay for a 400W when your real world power needs are less than 150W. The price for a typical good quality 300W is ~$50; 400 watters are often 50% more money.
Both AMD:s and INTEL:s modern processors can easily demand 65-70W by themselves (standard non-overclocked settings). Add to this the motherboard; the graphic-card, the memory-units, the PCI-cards and all the CD-drives. All can easily add up way beyond 250+ W
The question is whether you (or anyone) can run all these components at full tilt at the same time for any length of time in a real world situation. I can't really see how this can be done. Someone mentioned that playing or creating MP3s might draw more power; I have to try this soon.

It's true the test platform *only* runs a P4 oc'd to 2.12GHz (~55W) and the Matrox 400 Max graphics card probably does not draw as much power as the latest ATI and GFe cards. There are 2 HDDs, 2 optical drives and 512 mb of ram but the system is NOT crammed full of stuff. The max AC power draw on this at full tilt is under 130W; this means the PSU is delivering no more than ~90W. Even if you double it, we're still talking about just 180W.

Your own experience with the Antec TP PSU tells a lot about real power needs -- the fans in that model are calibrated to up the voltage from the min 5V only when the PSU is delivering ~150W or higher in a typical 25C environment. What does that tell you about how much power your system is drawing?

As mentioned above, check this thread for more info.

PS -- I have sent emails to nVidia, ATI & Matrox inquiring about the power dissipation of ther various cards; they don't provide this info anywhere on their sites. AMD estimates 10W for the VGA in their system guide.

Ralf63
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Post by Ralf63 » Fri Oct 04, 2002 11:49 am

MikeC wrote: The original question here was: 300w or 400w for a modest 1.5GHz system?
Zokka also added: "The reason I ask is i don;t really want to have to buy another powersupply a few years down the line." (my underline). Maybe he wants to upgrade even further by then. Thats not an unreasonable assumption is it? My Antec Truepower 430W is an overkill perhaps, but the 330W version is a damn good and seriously quiet PSU, and I would recommend it to anyone. Better safe and sorry.
The price for a typical good quality 300W is ~$50; 400 watters are often 50% more money.
Why so price-considerate all of the sudden? My experience from browsing through many of these PC-forums - regardless if they are "overclock" and "noise-muffle" oriented - is that many of us computer-geeks are villing to spend substantial amounts of both time and money (way more then the average low-end brand-name PC-user), just in order to tweak our systems exactly right. It almost becomes a self-feeding goal by it self. The money spent is of less importance.

Now, presuming we all want to avoid the cheapest "El-cheapo" power-supplies, then most quality PSU:s (thats also seriously quieter then the avarage) is likely to cost more money anyway. Take the Zalman ZM300A-APF PSU, for example. The pricetag for the Antec Truepower 330W PSU is around $65 by the way. Big deal?

Vincent
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will a system need 300W+ power supply

Post by Vincent » Fri Oct 04, 2002 11:59 am

depending on your system configuration:

for PC application (non OC purpose)

1. even the CPU (single) up to P4 2.8GHz and with all heavy loading components such as VGA card, sound card, CD_RW, SCSI HD*3...., the maximum power will be around 150W, but the peak power should up to 250W especially in initial stage
please refer to Intel PSDG
http://www.formfactors.org/developer/sp ... PSDGV1.pdf
2. P4 change from VR8 to VR9, that means +5V will be no more important, even a 550W dual Xeon only need 5V/20A 3.3V+5V<140W, the reason why to keep 5V/30A in PSDG just cover old P3 (VR8 use 5V for CPU), the large 5V will make the P4 system unstable (normally P4 MB need 5V<2A)
3. Check the peripheral connector on your PSU, if you want to draw 300W+ from your PSU you might need more than 8~9 peripheral connectors.
4. The advantage to use a 300W+ PSU: more capability and reliability in derating mode
5. The disadvantage to use a 300W+ PSU: no protect function for OCP, OPP
6. Intel PSDG 300W has 440W+ capability (3.3V/28A, 5V/30A, 12V/15A, 5Vsb/2A) and the protect limit in 300W, that's the advanced power sharing design and meet the real system requirement, just like the pipe and highway design to deal with the dynamic flow

for Server application (or work station)

1. Please refer to SSI PSDG (EPS12V)
http://www.ssiforum.org/docs/EPS12V_Spec_v1_6.pdf
2. All the server use VR9 (12V) for CPU design to deliver high power but keep the similar wire harness
3. The 12V could deliver 240% power than 5V in the same wire
4. The excellent capability of 12V could handle more than 20 SCSI HD for server requirement
5. SSI connect change from 20P+4P to 24P+8P, 3 more 12V wire could deliver 216W safely (each wire could deliver 6A safely but 9A for capability)

then you will know what's the problem of a 500W PSU could provide only 300W capability for ATX wire if you don't have 10+ peripheral connector

The PSU could not provide more power if the system doesn't need it, just like a 911 twin turbo could output 500HP but with a output limit in 100HP.

MikeC
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Post by MikeC » Fri Oct 04, 2002 1:40 pm

The price for a typical good quality 300W is ~$50
Oops, I meant to type $60 :oops: ; the 400 watters seem to run $80~100.

Ralf63, I don't think my concern about price is anything new; isn't it a factor for most purchases? Don't we all love a deal or not to spend more than we have to? At least half the site's mods/projects are about making cheap DIY solutions that work well. At the same time, I totally agree that PC nuts (me included) spend ridiculous amounts of time, energy and money on getting just what we want.

My main point remains: real world power requirements for desktop PCs appears far lower than recommended by Intel & AMD. Vincent's post substantiates this POV thoroughly and technically; thank you, Vincent, for those PDF doc links -- they are now permanently in my ref directory. Actually, I think the CPU mfg's recommendations are less relevant than what big system integrators like Dell, HP, etc actually do...

A case in point: The Gateway 700XL was noted in our IDF coverage article as having a PSU fan on the side over the CPU. This model received an Intel award and has been shortlisted by most mainstream review sites such as ZDNET as one of the most powerful, fully loaded PCs you can buy, with high performance video editing capabilities, etc. Here's a C\NET review: http://computers.cnet.com/hardware/0-10 ... ag=rev-rev. The 700xl, even with a P4-2.8GHz, uses just a 250W PSU!!(confirmed by a Gateway tech).

Even mainstream reviewers wouldn't rate a system highly if it was unstable, would they?

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