Power Supply Statistics
 

I'm configuring my new linux system and unfortunately I'm stuck (at the moment) with a low power supply. My new graphics card requires a minimum of 300 watt supply and I have an iomega external firewire drive hooked up as well. I'm stuck with a Dell Dimension 2400 that came with a supply of 200-240 according to Dell (depending on what's really in there). Can anybody tell me how I can view the details of how the unit is performing? Is there a command that will output usage at any given time?

Thank you.

On desktops, there is no meaningful way of measuring power usage, because the supplies are often not metered. With laptops, the power monitoring is necessary so that batteries can be managed, and the acpi interface can be used.

You might be able to get hold of an external power meter (the sort that plug into the wall). They typically retail around $30-$60 dollars. Sometimes you can borrow them from community groups with an interest in energy conservation, or you could split the cost with friends.

The other point is that it isn't just the typical energy consumption that matters, but the peak. A modern graphics card can vary greatly in power usage, depending on what it is being used for (a 3D game at peak frame rates would be the way to push it for testing). Power supplies will typically do a (recoverable) thermal shutdown if they are overdrawn, but you are taking some risk of complete supply failure with an under-specified supply.

I kinda figured since there were so many views and no replies this might be the case. Thanks for the reply neonsignal. So i guess my question should be rephrased and ask "is it unwise to run my system this way with an under powered supply?". Resources are scarce at the moment so im stuck with this one until most likely after Chrismas. On second thought, can anybody recommend a low cost PSU? I can scratch up 30 dollars or so. Whats a good budget brand?

Everything else about this system has been pretty much flawless. My usb external drive works. My usb m-audio microphone works. Sound works. Flash, java...everything just works practically right out of the box. I'd be a bummer if i fried something due to an underpowered PSU.

I'm new around here so any comments are appreciated.

Hmmm...I think you might have more than one problem.

Dell Dimension 2400 is an older i845 chipset system. Its only got an AGP and PCI slots. GT430 is (as far as I know) only avaible in PCIe, so its not going to work in the old 2400.

As far as the 'required' 300watt power supply goes, thats not exactly true. nVidia says 300watts for various reasons, mostly due to the changing nature of power supplies (a few years ago they had much higher amperage on the 5v rials than now). Also because lots of 'yum cha' power supplies are around, and a lot of them are sold with a wattage sticker saying whatever the manufacturers think will sell, not what the power supply is capable of delivering.

The TDP (thermal design power) on GT430s is 49-60 watts (49 watts normal versions, 60watts 'OEM' vesions). Max power requirments for the GT430 is similar to the TDP. With a low power CPU total draw under 100% load could be as low as 75 watts, but the old P4s are pretty power hungry. I would guess that max draw would be in the order of 150-175watts....

Now, you might be thinking 'cool, I have enough power then'. Sorry, but maybe not. As power supplies age, the max avaible power drops (due to aging caps, etc.). The cheaper the power supply, the more likely the max power has dropped. Since dell tends to use fairly cheap parts, and the 2400 is a 8 year old machine, I would guess that your max power could be as low as 125watts.

It is possible to get power supplies for $20-30 or so, but I wouldnt. They are more likely to be 'yum cha' junk, unable to deliver the amound of power the manufacturer says it can. Voltage 'ripple' can be a problem with the really cheap power supplies as well.

IMO if you were going to get a new power supply for that system, get a 300-350 watt seasonic. Seasonic makes great power supplies, and the 300-350 watt models are avaible for $35-40 US.

Excellent Info here thank you cascade9!

Thank you for the recommendation! I'll look up the Seasonic brand. Would there be any danger in going in the opposite direction by getting a supply in the range of 400-450 watts?

OKay, this has me wondering... removing the case door (what a concept!) reveals this info. Looking at the photo I took, does this mean the supply is rated at 300W like other supplies would be listed at retail? I'm confused. :/


https://picasaweb.google.com/lh/phot...eat=directlink

Ok, now I feel a little silly...after looking around, I did find a GT430 in PCI (ZOTAC ZT-40605-10L GeForce GT 430, if you've got a different brand I'd like to know if you dont mind). I'm not that suprised, there has been PCI nVidia cards for ages, just I hadn't seen a GT430 in PCI till I found that Zotac model.

Dell doesnt spec the power draw, and finding the 'real' power consumption can be tricky. Its easy enough to hook up a power meter, like neonsignal suggested, but that just tells you the power consumption of the system as a whole, not how much power the internal parts need. It doesnt tell you how efficient the power supply is.

Thats nVidia guessing again. Unless I've made some stupid mistake (totally possible, LOL) Watts = Amps x Volts. So 12v x 22amps = 264watts. Which is, ohh, about 200watts or so more than the video card needs. The video card itself only needs 12v x 5amps = 60watts. Its also more than the i7 930 + GT430 would need as well.

You _might_ have enough power from that 300watt power supply, but I wouldnt risk it.

As for the difference between the power consumption of the P4 and a new i7, to be really accurate its complex answer. The short version? Older systems, like the P4, have less difference betweeen 'idle' power consumption and 'full load' power consumption. That is because newer systems than the P4 have various tricks in use to lower power consumption at idle (downclocking he CPU, lowering the CPU voltage, etc.).

The P4 systems also used more 5v, and less 12v than more modern systems. That is why your 300watt power supply is rated-

3.3v = 20amps
5v = 30amps
12v = 13amps
3.3v + 5v max draw 175watts

Compare that to a more modern power supply, like a seasonic SS300-ES-

3.3v = 18amps
5v = 20amps
12v = 24amps
3.3v + 5v max draw = 120watts

Its not the same, or even that close to what a modern 300watt power supply delivers.

No, there is no risk going up to 400-450watts. It can have an effect on efficiency (at very low % of 'max' power draw, efficiency falls off) but it shouldnt cause you any problems. Power supplies deliver what the system needs, no more. ;)

IMO its probably not worth it, unless you were planning on installing it into a newer system later. Getting a quality branded power supply rated for 400-450 watts is a fair bit more expensive than 300-350 (for seasonic, you are looking at more like $80 to get a power supply that is 400watts+, so pretty much twice the price)

Newer systems tend to state 'minimum power supply 500wats' (even if they dont need it, but thats the same thing as nVidia does), so if you do go bigger, maybe 500watts is a better idea.

Yep. That's what I'm using. 3D works fine tested on Neverball. As far as DVD playback, I lose a few frames here and there. My CPU runs high during playback. I'm wondering why the GPU can't take more load off the CPU. I'm guessing it's the slower bus speed of the Dell 2400 chipset in general.

I have no issues so far with the power supply. Thanks for all your advice so far. Much appreciated.

You probably need (O.K., dont 'need' but want) to use VDPAU (Video Decode and Presentation API for Unix), aka 'hardware video decoding'.

http://en.wikipedia.org/wiki/VDPAU

I've never used VDPAU with openSUSE, and the SUSE wiki has removed the 'guidance and hints for VDPAU with openSUSE' page (linked from the general nVidia page)

http://en.opensuse.org/HCL:Nvidia_video_cards#VDPAU

Pity. Still, you might be able to get it going without the help page. I'd try mplayer or one of the mplayer variants (gmplayer, kplayer, etc.), they are the easiest to get VDPAU working with in my experience. ;)