Power supply question

I am still in the process of upgrading my sister's computer (question about switching from IDE to SATA hard drive earlier) and I have now hit a hurdle with the power supply.

She has a desktop case (which she will not change), so I was just using that and upgrading all the components. The only thing I am reusing, apart from the case, is the floppy drive. So, I ordered a new power supply, but it is too big. A local computer shop didn't have one the same size, saying they were specific to the case, so I take it these are special-sized components. Will I be able to get one at all? I am in the UK.

The one she has is 300W, but I wanted to get a more powerful one to run the newer components. I had to get converters for the power connectors, as the new hard drive and DVD writer are SATA and the existing PS did not have the necessary connectors. It looks like we may be forced to stick with that one, or else she needs to get a tower case. I have never worked with a desktop case before, so was unaware of this discrepancy in size.

 

There are several 'standards'.
You obviously need a psu to match the mounting screw and fan outlet positions, as well as the physical cube dimensions.

If it doesn't say something like NLX or SFX on the psu label post some pics and dimensions.

 

Can you see the brand and or model of the case? I have to agree with above there will 3-4 standard size dimensions for BTX....ATX...Midi etc etc cases and then there are PSU for those dimensions. The defined dimensions may limit what choices you will have.

 

If it is one of the Cooler Master Cavalier desktop cases, they have a proprietary size PSU that isn't a member of the common form factors.

.bh.

 

OK, thanks. I will check when I get home and see what I can find.

Ooh, zepper, I've just noticed your location - we were there many years ago, beautiful place.

 

It's a bog-standard beige unmarked desktop case, which she bought from a local PC shop a couple of years ago, or more (I was unavailable at the time to do the job and she became a little impatient to get a new PC). The PSU says Q-TEC, model ADT-300 and it measures 15cm x 8.5cm x 11cm approx. There is a 'Supports Pentium 4' sticker on it.

 

Just some info you may want to know:

I have an HP Vectra VL400 pc which came with it's own HP branded custom psu which cannot be replaced other than one from the same line. It's also a desktop case such as the one you are speaking of [the type that looks like a vcr. Well I didn't like it so I bought a new case. & since the psu was small and shaped to the proprieties of the desktop case I still went on! How? Well I bought a nice mid tower atx case and bought a standard size psu. I noticed that the custom small hp fan [which would not fit in the new tower because it was to small], had an extra wire coming out of the psu that attached to the motherboard of my pc. [Kind of like an intrusion chassis wire]. I thought to myself why would a psu need to communicate with the motheboard if all it's doing is providing power? So I decided to use a small jumper [the kind you use on hard drives], and place it where the psu's "extra wire" attached to the motherboard. Sort of like to emulate the fact that the wire were connected with it using a jumper on the motherboard instead. I plugged my new standard size psu and BOOM IT WORKED! Has been working ever since! Years now!

Seems to me that they do this so you use a company made custom psu. The jumper placed on the mobo tells the mobo that the custom psu is connected even though it's not. So if your psu has an extra wire coming out that attaches to the motherboard try it! And for hecks sake get a nice normal case. Those desktop cases are so outdated.

:major


Good luck!

 

This is not a branded computer at all, just a plain case made up by a small computer retailer. I think they're out of business now! I can't see any extra wires coming out of the PSU.

If it was up to me I would use a tower case every time, but my sister wants to keep the desktop as it fits into the tiny space she has in her bedroom for her computer and associated bits. It is quite a huge beast, but she puts her printer on top of it to save space, which she can't do with a tower case. If this PSU does not cope with all the new stuff being installed, she will have to get a tower case and rearrange the bedroom. She has loads of stuff there she never looks at anyway. She's a hoarder, and it's only a small cottage she lives in. You can hardly move about, she has so much junk! I digress!!

 

Would this be it?

 

That be the one!!

I've put all the new components in, but haven't fired it up yet. I did some research about this PSU brand on the Internet, and it appears that in some cases it's been the cause of some performance problems, and I'm now beginning to wonder whether this has been the source of the problems in this case, as this computer has been struggling with the simplest of tasks for some time, despite having all the disk maintenance measures. Even the Internet connection is slow - it's broadband but it's like dial-up.

 

Perhaps you'd like to recap why you need extra power?
Make a list of components drawing power and check the total. Post it here so we can help.
I would be suprised if it cactually came to more than 300 watts. (Qtec list a 350w version).
However it is not only the total power you need to check. All power supplies have limits to the current they can supply on each different voltage. I see there is a list on your psu label. With most psus, if you multiply each voltage by its theoretical maximum current supply to get theoretical max power for each you will find the total more than the rated power. This is because you can trade off one load against another. Few installations need all reails at full blast together.

Another consideration is that you can't increase the power input without a heat penalty. This is particularly significant in 'compact' style cases.

I notice that several equipment suppliers are offering 'refurbished' units. I don't have one of these units, the pic came from a UK Ebay sale of a brand new one. Some more details from you might help, the sizes you quote are definitely non standard. What space do you have in the chassis?

You can check performance by temporary substitution of a different supply, not located in the chassis.

 

Thanks for the extra info, studiot, but I have never gone into this in that much detail. In fact it's some time since I've delved inside a PC at all, except for some minor upgrade to our own computers.

I 'assumed' that, as it's an old system, the new gubbins I'm installing might need more power. I will have to check the specs as they are at home at the moment, but essentially I'm installing a new SATA hard drive, SATA DVD rewriter, IDE DVD ROM drive, all on a new motherboard, which was a mobo bundle complete with cpu, fan and memory ready installed. If memory serves, it's a Foxconn board.

It may well all work fine, we'll have to wait and see. It would have been an idea to test with a different PSU, I suppose, but I didn't have the time or inclination to look into her problem in any detail. I've been unwell for some time, and I am only just coming round to getting more motivation. It's obviously too late to test the original components with a different PSU now, but if it doesn't stand up to the task of the new components, then I will have to look into it, and she has now said that if all else fails, and we can't get a replacement, she will have to have a tower case.

 

Fancy graphics cards are the main gas guzzlers. I don't see you published list adding up to more than 100w, if that.

 

OK, that's helpful, thanks. She doesn't need fancy graphics, so we're going with the onboard one. No extra sound card either. No cards at all, in fact.

I will update with how I get on.

 

All seems well with the existing PSU with the new components. I've installed XP Pro and a few programmes, set up the Internet connection, and transferred all the backed-up documents onto the system, and it appears to be working smoothly so far.

Thanks again for the advice.

 

Glad it's going again. Remember to keep it clean inside.

:major:major