Solved desktop power supply - importance of wattage

September 8, 2011 at 00:02:27
Specs: Windows 7 Home Premium (x64) Service Pack 1 (build 7601), 2.60 gigahertz AMD Athlon II X4 620 / 5887 MB
A friend has asked me to help her in choosing between the Dell Inspiron 620 or the Inspiron 620s Desktop. The only difference between the 620 and the 620s other than the 620s box being thinner and therefore cramped inside, is in the power supply. The 620 power supply is 300W; the 620s power supply is 250W. What is the significance of the 50-watt difference?

Thanks


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✔ Best Answer
September 8, 2011 at 13:28:12
" .....it's when you begin upgrading it with, for example, more drives or a more powerful video card, that you need to look at upgrading the PSU so it can cope with the extra demand."

Addtional hard drives and optical drives draw very little power.

If your friend thinks they will NEVER need to install a video card in a slot on the mboard, it doesn't matter which model he or she gets.

However, if your friend ever installs a video card in a slot....

Your power supply must have at least the minumum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD!)
You can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements.

You MIGHT be able to get away with a power supply capacity 50 watts less than the minimum stated for the video chipset, but NOT likely more than that.

The 620s has an oddball proprietary sized power supply.
They cost more to buy for the same wattage capacity, very few video cards you can install have a video chipset that will be okay with a 250 watt PS on the system without frying the power supply eventually, there may or may not be replacement power supplies that will physically fit in the same space as the original one that have a higher wattage capacity, and if there are, the wattage choices you can get are limited and meagre.

The 620s may be able to use only low profile video cards - that limits your choices .
....

The 620 probably has a regular sized power supply, and if so, the choices of replacement power supply are unilmited.

The 620 probably uses regular height cards - lots of video card choices .

There are probably more avalable wiring connectors coming from the 620's power supply.

You can probably physically install more drives in the 620's case.



#1
September 8, 2011 at 00:31:19
To keep costs down, PC manufacturer's fit the lowest-wattage PSU that a particular system needs, based on the total wattage requirement of all the main components added together.

One of those Dell machines will maybe have extra devices or more powerful devices installed, therefore requiring the extra 50-watts.

Of itself however, the wattage output of the PSU has no bearing on system performance or Windows performance.

You can rest assured that the factory-fitted PSU is sufficient for that system, but it's when you begin upgrading it with, for example, more drives or a more powerful video card, that you need to look at upgrading the PSU so it can cope with the extra demand.


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#2
September 8, 2011 at 05:02:22
Amperage is what's important, especially on the +12v line. It's entirely possible that both the 250W & 300W have the same amperage rating on the +12v & the difference is in the +3.3v and/or +5v lines. You'd have to compare the power supply specs. Unfortunately, it's very difficult to upgrade slim style systems due to their 'non-standard' nature. Parts are available but the selection is very limited. My advice is to NOT buy the 620s system.

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#3
September 8, 2011 at 07:12:53
DELL PSU's are under-rated, 300w unit is capable of 350 or 400w. Any 105w tdp video card will work with dell 300w unit.

We can not fight new wars with old weapons, let he who desires peace prepare for war - PROPHET.


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#4
September 8, 2011 at 12:52:55
Pick the lowest price box. I doubt she needs much more.

Dell is like any other company. The stuff is just as cheap as can be. It just works for the common use.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#5
September 8, 2011 at 13:28:12
✔ Best Answer
" .....it's when you begin upgrading it with, for example, more drives or a more powerful video card, that you need to look at upgrading the PSU so it can cope with the extra demand."

Addtional hard drives and optical drives draw very little power.

If your friend thinks they will NEVER need to install a video card in a slot on the mboard, it doesn't matter which model he or she gets.

However, if your friend ever installs a video card in a slot....

Your power supply must have at least the minumum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD!)
You can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements.

You MIGHT be able to get away with a power supply capacity 50 watts less than the minimum stated for the video chipset, but NOT likely more than that.

The 620s has an oddball proprietary sized power supply.
They cost more to buy for the same wattage capacity, very few video cards you can install have a video chipset that will be okay with a 250 watt PS on the system without frying the power supply eventually, there may or may not be replacement power supplies that will physically fit in the same space as the original one that have a higher wattage capacity, and if there are, the wattage choices you can get are limited and meagre.

The 620s may be able to use only low profile video cards - that limits your choices .
....

The 620 probably has a regular sized power supply, and if so, the choices of replacement power supply are unilmited.

The 620 probably uses regular height cards - lots of video card choices .

There are probably more avalable wiring connectors coming from the 620's power supply.

You can probably physically install more drives in the 620's case.


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#6
September 8, 2011 at 16:10:44
@jefro
I believe the prices are the same.

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#7
September 9, 2011 at 05:09:12
I would go with the larger one, especially if there is any chance she may want to do any upgrades (video card, memory), but also because repair and maintenance is easier and parts like a replacement power supply would be easier to get and less expensive.

You have to be a little bit crazy to keep you from going insane.


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