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I really need some good advice on my PSU rail droop problems/PSU replacement options

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Old 11-06-04, 01:30 PM Thread Starter   #1
felinusz
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I really need some good advice on my PSU rail droop problems/PSU replacement options


I'm having some rather serious voltage rail drooping with my Antec TruePower 550W PSU. I took the time today to test my rails under load (machine fully overvolted and overclocked) with a multimeter, and was really shocked to see how low my rails are drooping.

My PSU's specs:

5V - 40A
3.3V - 32A
12V - 24A

Under load my rails droop to:

12V droops to a loaded low of 11.88V
3.3V droops to a loaded low of 3.22V
5V droops to a loaded low of 4.8V

My machine is running 100% stable right now, even when overclocked/overvolted to the degree that these rail droops were tested at; so the rail drooping doesn't seem to be compromising my stability right now, although it is almost certainly compromising any attempt for more overclocking.

Here's a list of every single overvoltage in my system that I can think of, as well as every single power-drawing component I can think of:


128 Megabyte ATi Radeon 9800 Pro
Mobile 2600+ Processor
Abit NF7-S 2.0
512 Megabytes of RAM
1 X 40 Gigabyte Maxtor Harddrive
1 X DVD ROM Drive
1 X CDRW Drive
5 X 120mm AOC Aluminum fans on 9V
1 X 120mm Panaflo M1A on 9V
2 X 80mm AOC Aluminum fans on 6V (baybus)
1 X 60mm fan on 6V (baybus)
1 X Swiftech MCP600 on 12V
1 X Dual Temperature Probe Panel
1 X Floppy Drive


CPU VCORE Voltage - 1.9V
GPU VCORE Voltage - 2V
GPU VDDR Voltage - 2.85V
AGP Voltage - 1.6V
VDD (NF7-S Chipset) Voltage - 1.8V
VDIMM Voltage - 2.9V


Now for my questions. Is this PSU inadequate for my current setup? The 12V rail doesn't have a ton of Ampage to it, and the 3.3V rail is heavily stressed by my heavily overclocked and overvolted graphics card, as well as my overvolted VDIMM.

What kind of options do I have for replacing this PSU? My financial situation is terrible, to put it bluntly, and I'm very reluctant (although I *can* afford it) to buy a new ~550W PSU for a large amount of money if it isn't going to give me some serious stability on my 3.3V and 12V rails in particular.



Any advice is really appreciated, especially on good replacement alternatives for my TruePower 550W.

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Old 11-06-04, 01:54 PM   #2
hafa
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The Antec True Power 550 has some of the highest amperage ratings in the industry (Thanks to this thread for the linkage to the table). You have many 120mm fans, however and given all of the other power hungry devices you have, you may even be stretching it a bit. Remember i=e/r and p=i*e; you might want to spend a little time and find out what your actual 12v amperage draw is based on your respective voltages and mfg specs. You may then find that you are drawing more than even the Truepower 550 is capable of putting out, or you may find that your PSU is not delivering as advertised, in which case an RMA may be in order (man, I love italics!).

If the PSU is delivering the advertised amperage, however, you may want to consider a 2nd smaller PSU to power all of your fans. Just make sure that it is rated at or higher than the anticipated load.

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Old 11-06-04, 03:06 PM   #3
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The PSU looks like it's feeling the strain a bit, but as long as it's stable it should hold out until you can afford a replacement. The voltage drop isn't much to be alarmed about just yet.

Not sure why the rails are dropping, it should be more than adequate for the system even with the overclocks, but if you've had it for a while I've recently seen some older CWT designs start showing up with bad capacitors after a couple years of constant use if they're being pushed hard. Might be worth popping the cover off and looking for bulging and/or leaking caps as long as you're not voiding any warranty remaining.

For a replacement, since you mention being on a budget, I would suggest the Fortron 530w, AX-500, or 550w.

You can get Fortron (Sparkle) at www.razorcomputers.net in Ontario - not sure they have the AX-500 Blue Storm unit yet, but it wouldn't hurt to ask. My 530w came from these guys - great service.

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Old 11-06-04, 03:41 PM Thread Starter   #4
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Thanks for the advice guys, it is appreciated.

Quote:
Remember i=e/r and p=i*e; you might want to spend a little time and find out what your actual 12v amperage draw is based on your respective voltages and mfg specs. You may then find that you are drawing more than even the Truepower 550 is capable of putting out, or you may find that your PSU is not delivering as advertised, in which case an RMA may be in order (man, I love italics!).
I'm sad to admit that I'm an ignorant when it comes to simple electrical math. How exactly can I calculate the power draw of my system?

Quote:
Not sure why the rails are dropping, it should be more than adequate for the system even with the overclocks, but if you've had it for a while I've recently seen some older CWT designs start showing up with bad capacitors after a couple years of constant use if they're being pushed hard. Might be worth popping the cover off and looking for bulging and/or leaking caps as long as you're not voiding any warranty remaining.
The warranty is already void (I changed the fans, and made everything modular)- I'll take a look in there, and see if there are any visible problems - what can I do if there are leaking caps though?


That new OCZ 600W PSU looks awfully tempting with dual 12V rails.... the $200 USD pricetag though...

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Old 11-06-04, 04:02 PM   #5
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Quote:
Originally Posted by felinusz
I'm sad to admit that I'm an ignorant when it comes to simple electrical math...
No worries, man...we all were at one time or another. It's pretty simple actually:

Amperage is referred to as i
Voltage is referred to as e
Resistance is referred to as r
Wattage is referred to as p

With this in mind,:

i=e/r or, amperage is equal to voltage divided by resistance (this is known as ohm's law; resistance is measure in units called ohms)

p=i*e or, wattage is equal to voltage times amperage.

So now if you have any two of the 4 values (amps, resistance, voltage or watts) you can calculate the ones you do not have.

Hope this helps!

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Old 11-06-04, 04:11 PM Thread Starter   #6
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That helps a lot - I knew what Amps, Ohms, Watts, and Volts were, just not both of the formulas that explain how they relate to each other

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Old 11-06-04, 04:41 PM   #7
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Quote:
Originally Posted by felinusz
I'll take a look in there, and see if there are any visible problems - what can I do if there are leaking caps though?

That new OCZ 600W PSU looks awfully tempting with dual 12V rails.... the $200 USD pricetag though...
If you know someone who's had experience soldering multi layer circuit boards, it may be possible to just buy and replace the caps (from a place like www.digikey.com) - provided they aren't oddball values that is. However, CWT has been very helpful to me in the past in answering questions about replacing caps with other values that will also work. Their website is www.cwt.com.tw, and should you need to contact them, your model would be the CWT-550AD. Be sure to get caps the same size/diameter - space is at a premium in these things.

The OCZ 600w is so expensive I don't recommend it at all ATM - in that price range, you can find PC P&C units; as well as a very nice new SilentX 600w unit made by Fortron. Topower makes the OCZ units, and I don't feel comfortable recommending such a high priced unit from them until I know for sure their build quality has come up enough to equal PC P&C and Fortron in terms of build quality and reliability.

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