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350 Watt PSU vs. 430 Watt PSU

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February 27, 2003 9:41:23 PM

I'm getting this case http://voyeurmods.com/VEXX-LE.asp and it's already pimped out in terms of fans and colors. It includes a 350Watt PSU, and since I'm upgrading from some crap that came with my Sony VAIO (which turned out to be a [-peep-] deal) I think that the 350 Watt will show an improvement.

Here's the catch: I can get a 430 Watt PSU for 33 bucks extra. Is this worth the money? I am going to be running an ASUS A7N8X deluxe with a Athlon XP 1700+ and overclock it to something over 2 Ghz, and I'll start out with 256 MB of Corsair 433Mhz Ram. The only card I'll have installed is A PNY Verto GeForce 4 Ti4200.

<Brendini>
February 28, 2003 1:29:35 AM

350 watt should be fine especially if the PSU is made by a well-respected company like Enermax or Antec.
February 28, 2003 5:19:06 PM

All you really need to make sure of is that the 12V rail on that PSU has more than 12 Amperes. 15A is enough but not overkill. The setup you are looking at will probably draw around 12A-13A off of the 12V rail. All of the other stuff will run off of the 3V and 5V lines. You should have more than enough.

<b><font color=red>Fredi</font color=red> <font color=red>Fredi</font color=red> He's our man! If he can't do it no one can!</b>
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February 28, 2003 8:06:11 PM

Thanks for the advice! That's a great way to check, because the site I'm buying it from has a lot of good info on the psu. Good rule of thumb to go by

<Brendini>
March 1, 2003 1:10:50 AM

I was wondering...

I have a couple of links for calculating the approximate power consumption for PC parts, but have no calc for working out ampere draw.

Gotta linky?

<b><font color=blue>~ <A HREF="http://forums.btvillarin.com/index.php?act=ST&f=41&t=32..." target="_new">Nice sig 81.</A> ~<font color=blue></b> :wink:
March 2, 2003 11:16:31 PM

Sorry, I normally use the specs and calculate based on the needs at hand.

I mean, I nomally just use Ohms Law to calculate something in terms of Watts and then back into what unit I need.

<A HREF="http://users.breathemail.net/roybeardmore/Related/Elect..." target="_new">Basic Formulas Page</A>

<b><font color=red>Fredi</font color=red> <font color=red>Fredi</font color=red> He's our man! If he can't do it no one can!</b>
March 3, 2003 2:41:12 AM

im inclined to go for the 430Watter... as you ARE planning to overclock considerably.
Overclocking does suck the juice, and its allways safer to err on the side of caution. An underworked psu will last alot longer than an overworked one!

<b>"If spam wasn't totally bogus, Hotmail users would be well-endowed, slim people with hair who make big money working at home and having great sex provoked by free porn and herbal Viagra.</b>
March 3, 2003 5:07:25 AM

Go with the 430 watt supply, call it "Future-proofing".

You will most likely outgrow the 350 after a while and will end up buying the 430 (or better) anyway.



<b>(</b>It ain't better if it don't work.<b>)</b>
March 3, 2003 1:07:40 PM

I would go for the 430W with those OC plans.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
March 3, 2003 4:18:10 PM

Overclocking will take more but not as much as you guys are thinking. (Depending on the overclock.)

I mean try it this way.

Based on the processor type and model. Let me use the AMD XP3000+. Based on the fact that it is a Model 10 design. The max ampere draw at 1.65V is 45A. (See page 21 of the AMD Athlon™ XP Processor Model 10 Data Sheet. Publication 26237B—February 2003)

On that setup, the stock setp, the draw on the 12V line is 1.65V x 45A = 74.25 Watts

74.25W divided by 12V = 6.1875A on that 12V line.

If you overclocked it by changing the voltege say up to 2.25V, the draw should be 8.4375A on the 12V line.

This new 8.4375A plus 5A from the other components is ~13.5A. A PSU that can supply 15A @ 12V should be fine. Of course it wouldn't hurt to have more amps but it would not be needed.

So depending on what you are looking to do will tell you what you need from a PSU.

<b><font color=red>Fredi</font color=red> <font color=red>Fredi</font color=red> He's our man! If he can't do it no one can!</b>
March 3, 2003 4:27:02 PM

But he will probably also OC the FSB and memory that will draw more power from the 5V and 3.3V line.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
March 3, 2003 4:47:50 PM

So?

Most PSUs have way more than enough amperes for the 3.3V and 5V lines.

<A HREF="http://www.newegg.com/app/Showimage.asp?style=album" target="_new">A decent PSU like this one by Fortron</A> is more than enough with 15A @ 12V. (I have three of these) $32.00 and free shipping from NewEgg. It has more than enough for the 3.3V and 5V needs. 28A @ 3.3V and 30A @ 5V. Remember to note that this is a 300W PSU.

All I am saying, not aimed at you personally, is to be carefull not to buy for the want of Watts. Or for tons of Amperes on the 12V line. Buy what you need and maybe more if you like. But buy for the right reasons. I picked up a 420W Enlight PSU for $39 with free shipping from them and it has 18A @ 12V. This is more than I will need.

<b><font color=red>Fredi</font color=red> <font color=red>Fredi</font color=red> He's our man! If he can't do it no one can!</b>
March 7, 2003 10:45:08 AM

Most PSUs can't maitain a high load on both the 12V and 5V/3.3V (often combined) at the same time. High quality PSUs often can though.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
March 7, 2003 7:11:58 PM

I agree, but most people don't max out the 3.3V, 5V, and lines when using a good PSU. They normally max out the 12V while putting average stress on the 3.3V and 5V lines.

Let's run down the list on each of the lines with above normal conditions. (Extra Hardware)

3.3V

Motherboard - 3.0A
AGP Card - 3.0A
Sound Card - 0.5A
NIC - 0.5A
Extra Card 1 - 0.5A
Extra Card 2 - 0.5A

Total on the 3.3V line = 8.0A. 8.0A * 3.3V = 26.40 Watts



5V line

Motherboard - 2.0A
4 128MB Memory Modules - 8.0A
Modem - 0.5A
Sound Card - 0.5A
NIC - 0.5A
Extra Card 1 - 0.5A
Extra Card 2 - 0.5A
2 HDDs - 1.6A
CD-RW - 1.2A
DVD-ROM - 1.2A
FDD - 0.8A
2 USB Devices - 1.0A
Keyboard - 0.25A
Mouse - 0.25A

Total on the 3.3V line = 18.8A. 18.8A * 5V = 94 Watts


So the total Watts consumed at this point is point before the processor is 120.40W.


Now let's add in the processor

XP1700+ @ 1.733 (Same consumption as a XP2100+) = ~7.49A on the 12V = 89.88W


That is 210W-225W. If the PSU is a decent one like I have listed above. A 300W PSU with power well allocated over the 3.3V, 5V, and 12V lines will be more than enough.

What I normally see are bad PSUs with 12-13A on the 12V rail. This is inadequate for the regular user.




<A HREF="http://forumz.tomshardware.com/community/modules.php?na..." target="_new">THGC meeting? Would you go if there was one?</A>
March 8, 2003 12:25:09 AM

If I may add a little point.

Keeping to the thoery that you shouldn't (if you can help it) use more than the 70% (which will keep the heat down and extend the lifetime) of the PSU's rated capacity, 225W would equate to 322W, which would suggest that the recommended minimum PSU for this particular setup is 330W.

I would throw in a 350W-400W to allow for possible requirements from upgrades: either more parts or hungrier ones.

<b><font color=blue>~ <A HREF="http://forums.btvillarin.com/index.php?act=ST&f=41&t=32..." target="_new">Nice sig 81.</A> ~<font color=blue></b> :wink:
March 8, 2003 4:39:36 AM

What's a good site to go to to learn how to test voltages on a motherboard? I have a little Sun-pro multi-meter that would probably be sufficient, no? I wanna tinker with one of my antique computers. :smile:


<-----Insert witty sig line here.
March 8, 2003 11:35:46 AM

You forget that one many (low quality) PSUs 3.3+5V load may need exceed 150W. With 120W you're pretty close to that maximum.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
March 9, 2003 1:02:33 AM

I agree with you guys. I was basically using an overclocked machine with a ton of extra cards, too many sticks of memory, excesive drives, etc. to merely demonstrate that most users will not need that much power under current conditions. I am sure that if we did a poll showing the amount of parts that people have in their systems that they would be far under what I had listed above.

However, for myself, I have my main rig using a 420W PSU with more than enough power and two fans for good airflow because I always caution on the side of excess.

<A HREF="http://forumz.tomshardware.com/community/modules.php?na..." target="_new">THGC meeting? Would you go if there was one?</A>
March 9, 2003 5:37:35 PM

I use 2*350W PSUs because one single PSU can't handle my crazy system.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
!