PSU HD molex modding, good idea or not?

[VirtualLarry]

I came across an interesting article on overclockers.com (of a technical nature, not one of Ed's biased political diatribes), about adding a capacitor inline in parallel with the molex connectors coming off of the PSU.

I would like to get the opinion of some of the tech-heads on AT, is this idea really, really smart, or really, really stupid? My first instinct upon reading the opening part of the article was, "a generic 300W for overclocking, and having problems? upgrade the PSU dummy!". Then I got to thinking, hmm, maybe this isn't a bad idea. It's basically analogous to the "reserve power" capacitors that are placed nearest the power/gnd pins of bigger ICs on circuit boards.

But I wonder what the real issue is here. I don't think that DVD drive spinup times are short enough, that adding a small additional cap would provide the additional power needed during that period for the drive. What I am suspecting is, that the generic PSU is actually supplying "noisy power", and that adding the cap is actually filtering out the noise moreso than briefly supplying the additional power needed during the spinup period.

I'm no EE, I'm a software guy, so if any hardware-heads want to comment, I'm all ears. Thanks.

 

[JPSJPS]

Per your request, an oversimplified analysis of that article by Ronald Dy Geronimo:
A charged capacitor will supply "reserve power" (constant current, not exponential decay) per this relationship:
T=V*C/I
T: time (seconds)
I: current (amps)
C: capacitance (farads)
V: volts
For a sample calculation let's try a 10uF cap(end of his article), 1 Amp supplied to DVD, and calculate the time for a 1 volt change (voltage drop) on the capacitor.
T (seconds) = 1*(10/10^6)/1 = 10µs per 1V drop on the capacitor. (10µs = 10 millionths of a second)

Obviously, you are correct that this cap will not supply any significant current during the DVD's much longer than 10µs startup time.

As to what his "fix" is doing in his article I do not know.
The capacitors on the power supply output are much larger than this 10uF so the additional noise filtering that you suggested is probably nil. Also, generally computer peripherals will include capacitive filtering on their power inputs so the external 10uF could be redundant.

What else is connected to that same power line in addition to the DVD? One potential wild guess suspect is an oxidized/corroded connection somewhere on this power line that "heals" itself shortly after current starts flowing. The cap supplies power until that "heal" occurs.

As an aside, believe it or not, this "healing" is occasionally reported (happened to me too) on telephone/DSL lines. The DSL connection is noisy and works poorly until the phone is being used and then the DSL connection works well. When the phone draws current the connection heals itself and becomes less noisy. It was VERY embarrassing to phone DSL support and by the time they answered the phone the DSL line was working well. I repeated these calls several times but the tech support knew about this problem. I cleaned all the phone connections exterior to my place and the problem went away.

The bottom line about that article is that his conclusion is bunk and something else is fixing his problem.
And his "fix" is not a universal fix that will solve others' problems. It is just not that simple.

BTW, "biased political" is redundant.
And, I am an old retired person so I agree with many of Ed's "diatribes" but I do not know which you disagree with. He is one of the few editors who takes the unpopular stance and tells it like it is. Some are far out but many make sense to me.
For much of the younger generation today, stealing is a way of life! They are too lazy to get an education and a good job so they steal from the productive members of society. I am referring to warez and P2P sharing in general. Then, they add lies to their repertoire and claim the moral path stealing from "evil corporations" or "overpaid entertainers".
If you live and work on the productive side of society as I did, then you tend to agree with Ed on this issue! If you are a luzer, then stealing is OK.
A person's views of many of his other "diatribes" will be based upon "which side of the fence" you are on.
That does not mean that I havn't downloaded a few MP3's, cracks, and movies though.

 

[DJFuji]

downloading cracks, mp3s and movies? Shame on you, JPSJPS! You should know better than that!

Thanks for the advice, as always. I don't understand half of it, but i'm getting there...

 

[Jiggz]

I've had this connectors before and in fact they still sell them over here Japan. But I took them off caused, they don't make any difference. Instead they are more obstacles inside the box than help.