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shearer
Northern Lights
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join:2002-06-18
Toronto, ON
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1 edit | Found this power supply calculator
Sorry if it's been posted before. I found this while reading up on power supply rails. Looks like it's quite up-to-date and more accurate than other calculators out there - they even put a useful notice at the top.
said by by the site :
The recommended total PSU Wattage gives you a general idea on what to look for BUT it is NOT a crucial factor in the PSU selection! Total Amperage Available on the +12V Rail(s) is the most important, followed by the +5V amperage and then the +3.3V amperage. Example: PSU you want to buy has 400W total wattage output but only has 16A on +12V rail. But your configuration might require 20A on +12V rail.
»www.extreme.outervision.com/psuc···ator.jsp | |
signmeuptoo
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| That is an excellent thing that they have done to point out the Amps per rail like that, perhaps more people will become savvy to this now, and when people come here and don't believe us, we can refer to it, perhaps.
A lot of calculators tend to make folks think they need more than they actually do, and this one does indeed also call for a lot. I wonder what their margin is...
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Traxless
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1 edit |  Excellent post. I was looking at the great deal Dell has for the Dimension 9200, C2D E6400, 1 gb of RAM, and w/o monitor for about $529 or so. The Dell PS is rated at 375 watts (made in China), which seems like it would be inadequate if you added a second HD and a quality video card for real game playing. This calculator seems to indicate that it would be a close call, which means problems down the road. Any thoughts?
»www.dell.com/content/products/pr···sd&cs=04 | |
BA
The Old Man's Gonna Roll the Hard Six
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| If you sit down and think about it, you'll realize a 375W PSU is more than enough to support any peripherals that will fit into the Dimension 9200 case.
Let's do the math. The Core 2 Duo has a max TDP of 65W. The dual-GPU 7950 GX2 requires a maximum of 143W according to nVidia. Optical drives pull about 25W each. Hard drives are 15W each. Assuming the processor and video card only use +12V, it would need ~20A on +12V. I guarantee you the Dell 375W unit can provide much more than that. | |
thender2
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1 edit | reply to Traxless
said by Traxless  :Excellent post. I was looking at the great deal Dell has for the Dimension 9200, C2D E6400, 1 gb of RAM, and w/o monitor for about $529 or so. The Dell PS is rated at 375 watts (made in China), which seems like it would be inadequate if you added a second HD and a quality video card for real game playing. This calculator seems to indicate that it would be a close call, which means problems down the road. Any thoughts? » www.dell.com/content/products/pr···sd&cs=04 375 watt PSU on a modern, semi-high end system?
Dell is a joke. A well funded, marketed, and maintained joke, but a joke nonetheless.
If it were good quality, maybe it'd get by, but it's dell.. they cheap out on everything, so no, it's not.
20 amps on the 12v rail is weak and doesn't leave much room for future expansion. You can get a $70 antec with two 19 amp 12v rails that is quiet, why go for a 375 dell?
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BA
The Old Man's Gonna Roll the Hard Six
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Vancouver, BC
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| As far as I know, the 375W from Dell has two 18A +12V rails.
Question: If the 375W isn't enough, then how is Dell shipping their XPS 410 and Dimension 9200 systems? After all, Dell lets you add two hard drives, two optical drives, an E6700, 7900 GTX, as well as a PhysX accelerator. Are those systems just dying after a week of use? | |
owenhome
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| reply to thender2
You don't need a power supply nearly as big as you think you do. Most of the power supplies on the market are total total junk. They claim 500, 600, 650 watts. But in reality, they are closer to 300 or even 200-250 regardless of what they claim or what's on the sticker. So to get enough juice for your machine, you have to buy these PSU's rated at 600 watts. What most people miss is that they are usually "peek" or "max" rated. Meaning they can put out that much power for about as long as a house fly takes to drop a steamer. Think about a car audio amplifier. A Legacy might say it has 1000 watts on it, but in reality, it's actually closer to 30. It might make 1000 watts for 1 tenhundredgagillionth of a second with a gun to its head, but that's about it.
Some of the PSU's on the market, like OCZ for example, rate their PSU's by what they can sustain. Like the 520 watt powerstream has a max of like 620 watts. There are a lot of really good power supplies on the market. But there's a reason why a good 500 watt power supply is over $100, and a POS 500 watt is $20.
Sure, a computer's current draw peaks at power up, but the actual constant load is far far far less than most people think, or would lead you to believe. Believe me, a 350 watt PSU that can actually deliver 350 watts, is waaaaaaaay more than adequate to power 99.99% of the computers out there regardless of their configuration. Sure something like an SLI/Crossfire configuration, or a machine with 72 hard drives might find this inadequate, but for any conventional PC, no matter what CPU is in it, will be more than satisfied with 350 watts. To be honest, it's not unusual to see a new machine actually use less than 100 watts of current wide open. 150-200 is closer to the norm. In fact, some of the Dell mini's had high-end P3's and ran more than fine on their 90 watt power supply!
Most of us will spend the money for a good power supply. One that makes what it claims. But I will guarantee you, a $12 500 watt power supply is going to make waaaaaaaay less power pegged to the friggin wall than a quality 300 watt power supply kicking along comfortably, regardless of what's on the sticker.
I will make no attempt to say Dell uses good power supplies. Frankly, they use crap. But, they are rated properly. That 375 watt power supply in the Dell probably puts out more juice than any $20 600 watt on the face of the earth. And thusly, would be far more than adequate. A true 375 watt power supply would run most any computer around, including most of yours. Unless, like I said, your a nut with 32 video cards in SLLLLLLLLLLI or 84 hard drives. Sure, there are lots of configurations when 375 wouldn't be enough. But for any basic machine, with just about any CPU, a "sane" video card, 1-3 hard drives, 2 opticals, and anything else a normal human being (not us) would run, it would be way more than needed.
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cibara
join:2006-06-02
Port Orchard, WA
| I enjoy threads like this. Something to dispel all the myths circulating around the web about power sources. I guess some of these computer gurus out there forgot how to use ohm's law. Not in this thread or forum, but definitely out there on the 'internets'. Good read.
Anyways, i am very pleased to see someone has done research on the power consumption of a 7950 GX2. A lot of people claim you need 35 amps for the card, which i cannot help but laugh at. About 150 watts peak is more reasonable, and factual. | |
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