Measured system power for my 8800GTS comp

[thilanliyan]

Got a Kill-a-Watt meter and just wanted to see what the power draw was. Here's the full specs of the comp:

E6400@3.4GHz With Thermalright U-120 with 2x120mm fans
Gigabyte DS3 with Thermalright HR-05 NB heatsink using 1x80mm fan
8800GTS (650/1000)
1x15k rpm SCSI drive
2xSATA HDDs (1 HDD with a Vantec Vortex HDD cooler)
1xexternal DVD writer
Antec P180 with 3x120mm fans
OCZ Powerstream 420

Soooo....with all that, and running RTHDRIBL, it was measuring about 350 watts. Phew...seems like I'm nudging up against my PSU capacity.

Also, just running Orthos to load the CPU, it went to about 315 watts.

At full idle it's about 265 watts. The idle is higher than I was hoping but I guess with all the OCing, it can't be helped.

 

[Munky]

I had a question about this issue for some time now: Your system draws 350W from the outlet, but your PSU has an efficiency of about 65%. So, am I correct in concluding that your system is only using 350*.65 or about 228W at the output end of the PSU? And isn't the PSU rated for it's output power, and not the input power? So in theory, you're only using about 228W of your PSU's rated capacity. Anyone care to elaborate on this further?

 

[thilanliyan]

Originally posted by: munky
I had a question about this issue for some time now: Your system draws 350W from the outlet, but your PSU has an efficiency of about 65%. So, am I correct in concluding that your system is only using 350*.65 or about 228W at the output end of the PSU? And isn't the PSU rated for it's output power, and not the input power? So in theory, you're only using about 228W of your PSU's rated capacity. Anyone care to elaborate on this further?

I think your assumption is correct. The PSU draws in X amount of watts, is transformed to the different voltages and sends out (efficiency) times X watts to the components.

The PSU would only be outputting that fraction and the rest is lost as heat. However, I think the efficiency is usually higher than 65% for decent PSUs.

 

[BassBomb]

Only 350?

THat would be sure to lay rest to those over inflated psu requirements everyone rambles about

 

[Navid]

According to this spec sheet, the efficiency for the 420W unit, at maximum load, is 63%.
http://www.ocztechnology.com/products/PSUSpec.pdf

So, the output power is 63% of the total input power. The input power was measured to be 350W.
So, the output power, delivered to the PC, is 63% x 350W = 220.5W.
This is not accurate because the efficiency is a function of power and we do not have the efficiency at 350W input power. But, it is close enough.

 

[thilanliyan]

Originally posted by: Navid
According to this spec sheet, the efficiency for the 420W unit, at maximum load, is 63%.
http://www.ocztechnology.com/products/PSUSpec.pdf

So, the output power is 63% of the total input power. The input power was measured to be 350W.
So, the output power, delivered to the PC, is 63% x 350W = 220.5W.
This is not accurate because the efficiency is a function of power and we do not have the efficiency at 350W input power. But, it is close enough.

I'm not sure how much of a difference that makes...but wow 63% sucks. It's still going strong though and has a 5 year warranty. I'm waiting to see if anything is able to break it.

 

[gramboh]

Wow my roommate just built a C2D E6400, 8800GTS 320meg, 1x 7200.10 320, 1x internal DVDRW, one case fan, factory HSF on cpu and I was worried telling him to get a 500W Silverstone. I was planning a 600W for a similar build, might go with the 500 Silverstone for $20 less.

 

[thilanliyan]

Originally posted by: gramboh
Wow my roommate just built a C2D E6400, 8800GTS 320meg, 1x 7200.10 320, 1x internal DVDRW, one case fan, factory HSF on cpu and I was worried telling him to get a 500W Silverstone. I was planning a 600W for a similar build, might go with the 500 Silverstone for $20 less.

If it's only $20 more then go with the 600w. That's what I'd do. But you know best about where to draw the line for yourself.

 

[PingSpike]

Originally posted by: BassBomb
Only 350?

THat would be sure to lay rest to those over inflated psu requirements everyone rambles about

Oh yeah, people have been pretty nuts on that for awhile now. Sadly, it still beats the old trend: put the cheapest piece of crap in the universe in there.

 

[slmcgra]

Originally posted by: thilan29
1xexternal DVD writer

.....
At full idle it's about 265 watts. The idle is higher than I was hoping but I guess with all the OCing, it can't be helped.

I was just curious... you mention the external DVD writer. I assume there is an ac/dc converter specifically for the dvd writer. Is this item part of the measurement? Because I believe these power bricks tend to use quite a bit of power on their own.

 

[Munky]

Originally posted by: thilan29
However, I think the efficiency is usually higher than 65% for decent PSUs.

I used to own a Powerstream 420W, and I was also surprised when the technical specs listed it at 63% efficiency.

 

[munisgtm]

nice information you shared thilan29...

 

[Navid]

These are good PSUs.
http://www.seasonicusa.com/images/BrochureManuals/Brochure1.pdf

 

[thilanliyan]

Originally posted by: slmcgra

Originally posted by: thilan29
1xexternal DVD writer

.....
At full idle it's about 265 watts. The idle is higher than I was hoping but I guess with all the OCing, it can't be helped.

I was just curious... you mention the external DVD writer. I assume there is an ac/dc converter specifically for the dvd writer. Is this item part of the measurement? Because I believe these power bricks tend to use quite a bit of power on their own.

It is an external brick but i have it plugged into the same surge bar as everything else.

Which do you think are better...PC&P PSUs or OCZ PSUs?? Are OCZs made by Tagan?

I've read that Seasonics are not as good as OCZs but that was just hearsay. What about Silverstone PSUs?? There's apparently a 650w PSU from Silverstone with 54amps on ONE 12V rail:
http://www.jonnyguru.com/review_details.php?id=100

Is it better to have multiple rails with like say 18A or one large rail??

 

[Elfear]

Originally posted by: thilan29



Which do you think are better...PC&P PSUs or OCZ PSUs??

PCP&C are some of the best PSU's out there. OCZ has good PSU's also but, for the most part, they are not as good as the PCP&C units.

Are OCZs made by Tagan?

Depends on which OCZ unit you're talking about. The GameXStream are made by Forton (the 600W and 700W models anyway). IIRC the Powerstream models were made by Topower but I'm not certain.

I've read that Seasonics are not as good as OCZs but that was just hearsay.

Seasonics have an excellent reputation and are some of the best out there.

What about Silverstone PSUs??

Silverstone are also excellent PSU's. The higher-end models are made by EMAC I believe and the lower end models are made by Enhance.

Is it better to have multiple rails with like say 18A or one large rail??

I would personally get a PSU with a single 12V rail. With most multi-rail PSUS, you have to worry about overloading any of the individual rails. Put too many components on one rail and you get random shutdowns and such. With a single rail you don't have to worry about that unless you exceed the amperage of your whole 12V line.

There is a pretty good list of PSUs over at Xtremesystems that breaks PSU manufacturers into tiers.

 

[BassBomb]

I guess I wont be upgrading my psu if i get a new system... unless i want quieter

 

[IEC]

Originally posted by: BassBomb
Only 350?

THat would be sure to lay rest to those over inflated psu requirements everyone rambles about

People don't realize wattage isn't everything

Watts do matter, but beyond a certain point are excessive.
Ripple/noise in the lines is much more of an issue - shouldn't have much of either.
Multiple 12V rails is just silly. Get one with a single +12V of 30A or higher.
Manufacturers fudge numbers - an el cheapo 500W puts out lower quality and potentially noisier power than my Antec True 430W, which is by no means that great of a PSU.

I've been using my Antec True 430W (not TruePower, there IS a difference) for 6 years or so and it has seen use in a s462, s754, s939, and now LGA775-based system. Now if my mobo didn't have a vdroop problem I could probably OC further...

 

[conlan]

The mega-watt PSU issue has been an ongoing debate in the GH Forum for some time.
Like SpartanNiner posted, total wattage isn't everything. There are 600+W PSUs that have weaker 12V rail(s) than some 450+W PSUs.

Your measured system draw at the wall socket is only telling you the total system draw, not where those watts are going.

The best article i've found on PSUs is Here
A very informative article from someone who really knows his stuff, and IMHO a must read for anyone about to invest in a PSU.

 

[Skotty]

I have a similar system, as well as one of those Kill-a-watt devices. I'll test my system tonight or tomorrow and post my own numbers for interests sake.

 

[rise]

sounds about right to me. measured with the kill-a-watt-

e6400@ 3.2, 1.4v
2x 1024
680i mobo
8800gts 640
2x 320gb
1x dvd/rw
2x 120mm, 2x 92mm
swiftech cheapie wc'ing
seasonic s12 500w

also included is a canon pixma printer, 19"lcd, 5.1 speakers, modem...

idle 295
2x prime- 330

 

[thilanliyan]

Originally posted by: rise
sounds about right to me. measured with the kill-a-watt-

e6400@ 3.2, 1.4v
2x 1024
680i mobo
8800gts 640
2x 320gb
1x dvd/rw
2x 120mm, 2x 92mm
swiftech cheapie wc'ing
seasonic s12 500w

also included is a canon pixma printer, 19"lcd, 5.1 speakers, modem...

idle 295
2x prime- 330

WHat do you get with graphics load?

 

[rise]

3d06 hit 375w (during firefly test)

 

[Zap]

Originally posted by: Navid
This is not accurate because the efficiency is a function of power and we do not have the efficiency at 350W input power. But, it is close enough.

That is true, close enough.

One thing not taken into account is how each of the voltages are loaded. It would be possible to be near overloading the PSU while still well within the "wattage rating." An example would be a 400W power supply with 20A on the +12v. So theoretically you can load up 400W worth of components (and be pulling 500-700W from the wall depending on efficiency) and have it working fine, or you could be pulling 300W from the PSU and have it tripping due to being overloaded - BECAUSE you are hitting over 20A on the +12v which is 240W by itself.

Originally posted by: PingSpike

Originally posted by: BassBomb
Only 350?

THat would be sure to lay rest to those over inflated psu requirements everyone rambles about

Oh yeah, people have been pretty nuts on that for awhile now. Sadly, it still beats the old trend: put the cheapest piece of crap in the universe in there.

What I tell people is essentially "enough wattage, as long as it is sufficient quality." For a while I was running my gaming rig on a measly 270W power supply with 16A on the +12v. However, it was a very good quality Enermax, which will actually put out every single one of those 16A sustained. I was running an Opteron 144 with 2GB RAM, one 7200RPM hard drive and an x850XT (later a 7900GT). I was unable to overclock with this PSU because of instability, but knew my components were good because of testing with a different PSU. Eventually I got a Fortron 300W unit that was capable of 22.5A, and with the same components was suddenly able to overclock the Opteron 144 to 2.7GHz. I think I was hitting the 16A +12v limit (192W) because I have a Seasonic Power Angel (same thing internally as the Kill-A-Watt) and I could barely push my usage to a bit over 200W at stock speeds.

Originally posted by: thilan29
Is it better to have multiple rails with like say 18A or one large rail??

I'd also vote for single rails, but it may not really matter because it seems that few PSUs are true multi-rail. Many are just single, that kind of gets divvied up to meet some kind of ATX spec on paper that Intel came up with (and since dumped).

---

I now have a 320W Enermax PSU with 24A on the +12v. I was hoping to build an overclocked C2D system with an 8800GTS, but don't look like that's a possibility. Note that my intent is a SFF using an SFX PSU, so I'm really limited in PSU choices and this Enermax has the strongest +12v that I've found - regular ATX PSUs are not a valid choice for this application.

 

[thilanliyan]

I just measured my Celeron D comp:

Celeron D 90nm @3.1GHz (stock cooling)
Kingston Valuram
Asus P5L-MX
integrated everything
1 7200rpm IDE HDD
1 DVD writer
2x120mm case fans

Results:
idle-->90w
orthos load-->140w

What a difference compared to my C2D comp.

 

[imported_Truenofan]

seasonic are quite nice, i had a 500 and only replaced it because i thought i was having problems, it was a s12, very quiet and very power efficient, i think it was in the low 90's