New PSU

I may be in the market for a new PSU pretty soon and I was wondering about a few things. I have my eyes on both a Fortron 530W unit that peaks at 600W for $75 and an Antec True480W that is in the same price range. Just wondering which is the better option.

I also heard that Fortron and Sparkle are essentially the same company...is there any truth to that?

Yes, Sparkles are rebranded Fortrons. For about the first time in my life, I'm going to recommend an Antec over a Fortron/Sparkle. The Fortron 530W has a rather weak 12V current rating of 18A. A system like yours would need well over 20A. The True480 delivers 22A, and the 12V rail is the largest consideration. Hitechjb1 tested the Fortron 530 a while ago and received disappointing results.

Alright, thanks Gautam....you always seem to have a very concrete answer to my problems.

Would it be better to get a lower rated Fortron since it seems to be the 530W that has bad amperage? Something like the Fortron 400W...it is going for $60 at newegg. I went and looked again and the Antec True480 is $90, and I may need something cheaper.

How do you determine they Amperage of the PSU that you are considering, what do you use it to judge, and how do you determine how much amperage is needed for a certain system. I am new to this area of computers, and I want to learn as much as possible.

Thanks Gautam...you and hitechjb seem to always make things understandable for me when you can.

I'm glad that I've been of assistance. . There are two models of 400W Fortrons; the GN and the PFN. The GN is rated for 16A on the 12V, and the PFN for only 15A. I've been convinced that you'd be taking a chance with either. Fortrons do often exceed their stock specifications, but you're running a risk in this case, as a 1700+ at 2.5ghz and 1.95v alone draws around 15A. My 300W is rated for 15A, also, and I haven't had any problems, but this is a combination of luck and my having a lower-end video card. Fortrons are all relatively weak on the 12V, which is the most important. As to selecting the right PSU for you, hitechjb1, as usual, has the answers. You may want to consider the True430; its only $80, and is rated for 20A.

well the amps are listed in the stats on the label/ site. and most people seem to recommend to me greater than 20A for the 12V rail. sorry i can't give you direct calculations, but on most things there is an Amp rating... like for a tornado its like 0.76 amps. I belive i have it right, but you might want to wait for Gautam and Hitechjb1 to back me up.

The processor is the main source of power draw, obviously. So, firstly, consider the power draw of your processor. 2.6ghz, 1.95v would draw just about 150W of power. Divide this by voltage line that its being drawn from, in your case, the 12V line. The result is 12.5, but you must also account for the efficiency, which most say is around 70%, so dividing 12.5 by .70 results in 17.8A. This is how much the processor alone will draw at full load. You also have to account for fans, etc. The video card is an uncertainty. No one knows for sure whether or not which video cards use the 12V, if any. If they do, then this is a major consideration. Hard drives and optical drives, do, for sure, though. So this is where the 20A figure comes from.

Ok thanks a lot Gautam. I also PM'ed hitechjb...and read through Larva's sticy thread on PSU's. I think I have learned quite a bit, but all of the Amperage and wattage stuff is really confusing for me...probably since I know literally nothing about electricity and how it works/how it is used. I need to fing a good beginner guide that explains all of this. *Runs off to Google to look*


Edit: Found a PDF document that looks like it may be helpful in grasping all of this stuff.

This is what I found...it seems to be pretty helpful, but I need something that is even more in Layman terms...i'll let you know if I find anything. http://www.the-cool-book-shop.com/freebooks/electronics_guide.pdf

Larva suggests the +3.3v and +5v combined rating as a basis of quality. This it can determine, but lately, the 12V has become more pertinent towards systems these days. The combined ratings indicates the quality of it, but not necessarily how well it would work for you. He's working on an update for his guide, though. Wattage is a measurement of energy; power and heat. Amperage is a measure for current, and voltage Wattage is, from chem class, the difference electrical potential between two electrodes. And no, I don't quite get what that means. Wattage is simply Amperage * Voltage. Divide any estimates by 0.70 to account for inefficiency. A processor's power draw is its (voltage^2 * clock speed)/stock vcore^2 * stock clock). Hope this helps.

I'm happy with my Antec SL400.

Altec,

Due to the importance of the 12V current for P4 system and some recent nfoce2 system (such as the NF7-S you have), I have done quite a bit of thinking and calculations, ... and is summarized in the follwing post.

Try to read it and see whether it helps your decision. That post does not require detailed knowledge about how to calculate those numbers, .....
Some thoughts on choosing PSU for overclocking recent motherboard, CPU, GPU, ...

Basically, it says one would need at least 20-24A on the 12V line for a typical overclocking system (since beginning of this year, for Tbred B and P4). When I did the estimation and calculation, I took into account various variations (due to specification change, part difference), number of components (HD, fan, video card, ...), whether a high performance video card uses 5V or 12V. I took into account there are different ways to do estimation of current, power, ...

Within that post, there are links to four related posts on

- some experiences with a 330W, 430W, 550W PSU for overclocking

- how to estimate current for typical overclocking systems with high power and current CPU such as P4 and Tbred B at high level of overclocking (if you like to look at numbers and calculations)

- importance of higher rated PSU to eliminate overclocking uncertainty for high level of overclocking


Brief summary for some basics:

I, V, R, C, L, P, f, ... are current, voltage and resistance, capacitance, inductance, power, frequency respectively. More basic concepts about I, V, R, C, L, P, f and their relationship requires some understanding about principle of electricity.

For a brief summary,
V = I R (voltage V across a resistor with resistance R and current I)
P = V I (power dissipation P in an element with current I and voltage V across)
Q = C V (charge Q stored in a capaictor with capacitance C and voltage V across)
I = Q / t (current I equals to the flow of charge Q per unit time t)

Here are some links to some basic terms involved in this post (also some more in the first post of this thread):

What is cycle time and frequency

What is the active power of a CPU at frequency f and voltage V

Relationship of clock, die temperature and Vcore

To get that last 100-200-300 MHz from a CPU, one would require a higher rated PSU and better CPU cooling. Whether it is a cheaper SK7, or SLK-800/900, or white water or cascade. The last few 100 MHz is very expensive and may cost $80-100 on a new PSU from a stock PSU, $50 for a top-end HSF and $150-200 for water. This is not cost-effective. This is something we have to think about whether we just want a practical computer system running 300 MHz slower, or want to spend the time and money to learn and try something new.

Wow, thanks a lot hitechjb1, you always semm to help me out when I need it. I will look over this stuff a bit and see if I can get some understanding of it.

Thanks again man.