PSU related questions

[26Dolphins]

Hi guys,

On my older P4/ 1.5GB RAM + Win XP SP3 machine, I've lately come across the following issue.
A few weeks back, a friend gave me a Seagate IDE HDD, which I'd like to use on the specific machine. When I connect it and turn the PC on, it starts and then in a couple of seconds sort of turns off (before the POST screen) and then starts again and boots normally.
Could this be a PSU related issue?
The current PSU is an OEM 500W one, about 4-5 years old, with no other signs of malfunction (it's silent and not overheating).

I was thinking of replacing it with a 600W one, but since this is an older PC, I don't want to spend much money. Thing is, all the ones I found in my area within my price range come with only two molex 4-pin connectors. I need at least three, so somebody suggested I get me a molex 1-to-2 connector which are ridiculously cheap.
Now, my question may sound stupid, but if a PSU is designed to allow only 2 devices of a certain type to be connected, wouldn't it be a bad idea to expand its capabilities and connect more?

Thanks in advance.

[Sope]

Here is a good site to help you calculate your likely power requirements :-
http://extreme.outervision.com/psucalculatorlite.jsp
It even includes taking into account the age of your PSU.

As for molex splitters, I've used those in the past without any problem. I believe they are a common way of expanding the number of available connectors especially on pre-built systems which often have the minimum required connectors as standard for the purpose of simplicity and cost saving.

As for your current PSU, 500W is a decent enough size and should cope easily with one extra HDD unless you have some other power hungry components in the box like a big graphics card you haven't mentioned?

[26Dolphins]

Hi Sope,

Thanks for reminding me about eXtreme Outer Vision (I even have it bookmarked).
I took the test again and it says that with all the devices connected (including the 2nd HDD) and 35% capacitor aging I'd need around 360W. So, taking the test didn't really help me understand the issue.

..unless you have some other power hungry components in the box like a big graphics card you haven't mentioned?

The machine runs on the integrated VGA, other internal devices (besides the primary HDD) are DVD-RW Drive (which is SATA but connected via a SATA-to-IDE cable, due to shortcoming of the PSU), Floppy Drive, modem.
It's actually a modest machine. I thought that the PSU is decent enough to connect the second HDD, but maybe it's getting too old and can't handle the load HDDs cause at boot.

So, you think I'd be ok to use a molex splitter.

Thanks.

[Remah]

Originally Posted by 26Dolphins

The machine runs on the integrated VGA, other internal devices (besides the primary HDD) are DVD-RW Drive (which is SATA but connected via a SATA-to-IDE cable, due to shortcoming of the PSU), Floppy Drive, modem.
It's actually a modest machine. I thought that the PSU is decent enough to connect the second HDD, but maybe it's getting too old and can't handle the load HDDs cause at boot.

So, you think I'd be ok to use a molex splitter.

It doesn't sound like you have an overload problem. It is unlikely that you've run out of headroom with so few components on a 500W PSU. I've had many drives in a P4 PC and never used more than a 400W PSU. Likewise with the splitter but see my comments below.

So I would check the drive first. Search the web for problems with the specific drive. Seagate may well have a specific problem logged for your model. A drive diagnostic/test program may find a problem or the SMART data on the disk may show there is an ongoing problem.

Re PSUs. The total PSU output is important but it is not as important as two other factors:

• What voltage does your technology use. As technology changes so does the reliance on a particular voltage. So a newer system board will have different profile across the supplied voltages (+3.3V, +5V, +12V, -12V) than your P4 board. For example, very old PC PSUs had no 3.3V. And as you've discovered your PSU and system board have no SATA power connectors.
• What is available on each output cable. Two different PSUs with the same total output are likely to have different output levels for each voltage they supply. I had one PSU that had heaps of power available but not enough 12V DC for my graphics card.

The specs for your PSU are often on the cover but they should also be available online. You can then check whether using the splitter will overload that output line.

Wikipedia is a good place for further background http://en.wikipedia.org/wiki/Power_s...and_efficiency

[Sope]

Under the circumstances I'm guessing it's most likely to be a problem with the secondhand HDD.

It may be worth opening up you box again and checking all the connectors are securely in place and that the RAM is seated properly. You may have dislodged something when you installed the drive.
Failing that, it's probably worth running some tests on both the HDD and RAM.

[26Dolphins]

Hi guys,

Thank you both for taking the trouble.

I did open my box and checked all connections. Then I decided to give it another try, and it all worked fine. I run some diagnostics on the HDD and it all came back ok, but I'll keep an eye on it for the next few days.

In the mean time, I remembered that at some point I noticed something not being right with the "ATA/IDE Configuration" in relation to the OS in use (sorry, can't remember the exact wording) and made a change.
Trouble is, I can't remember if the altered setting was about the same time I had the issue with the 2nd HDD, but I'm sure I didn't try the HDD after making the change in the BIOS. Could it have something to do with a BIOS setting?

If I can spare myself the PSU replacement, I'd rather invest the money on getting a little bit more RAM


On a side note, why does eXtreme Outer Vision emphasize on "if you plan to keep your PSU for more than 1 year"? Are you supposed to repalce it after one year? I always thought you choose a PSU for the long run.


Thanks again.

[Sope]

Originally Posted by 26Dolphins

On a side note, why does eXtreme Outer Vision emphasize on "if you plan to keep your PSU for more than 1 year"? Are you supposed to repalce it after one year? I always thought you choose a PSU for the long run.

I guess some of the more enthusiastic people like to upgrade frequently!

Anyhow, glad it's going ok now.

[Remah]

Originally Posted by 26Dolphins

On a side note, why does eXtreme Outer Vision emphasize on "if you plan to keep your PSU for more than 1 year"? Are you supposed to repalce it after one year? I always thought you choose a PSU for the long run.

There are at least three reasons I can think of for building headroom into your calculation of PSU capacity so your PSU will last longer. I guess that the comment relates to custom rigs that are probably overclocked:
- Components deteriorate over time. Capacitors are probably the worst and the most likely to cause you problems.
- Steady state versus peak loadings. Leave enough headroom for short term spikes in power use - maybe the calculation already allows for it but it is OK to make a larger safety margin. The same applies to buying audio speakers for your amplifier, you should have a comfortable excess of average output to cope with the transient peaks.
- If you're overclocking components then the last thing you want to do is to cut them off at the knees by stressing the PSU which is not as expensive as the CPU or system board.