Page 1 of 3 123 LastLast
Results 1 to 10 of 27

Thread: clever PSU workaround needed

  1. #1

    clever PSU workaround needed

    Hi everyone!

    I was hoping you guys might be able to help me solve a tricky problem. :?

    I have a Compaq Presario 6150UK PC, which uses a MS-6553 motherboard (CPU is an AMD Athlon 2100+), and runs off a Compaq PDP-121P power supply. Compaq machines have something of a reputation for being awkward to upgrade, often using proprietary wiring arrangements in order to force users to buy replacements from Compaq.

    This has proved to be the case with me. I recently bought a new graphics card, a GeForce 7300GT, which I installed into my single AGP slot. However, most games and benchmark applications showed numerous graphical artifacts, which I realised was due to my inadequate power supply (220W, only supplies 5V on the 12V rail). Clearly a new PSU is needed.

    However, my motherboard/PSU connection uses proprietary wiring which doesn't conform to the ATX standard. So changing to a more powerful standard PSU would also require me to buy a new motherboard/CPU, which I don't want to do for at least another year. To make matters worse, my MS-6553 motherboard doesn't appear on either Microstar's or Compaq's websites, so I can't even get the specs to check the differences in wiring.

    I have a couple of ideas, but they both seem flawed:

    1. I could buy one of those new dedicated PSU that directly powers the graphics card, thus bypassing any motherboard incompatibility issues. However, I get the impression that these are PCI-e only. If that's the case, I would need a PCI-e -> Molex converter, and I don't think these exist (I've only seen Molex -> PCI-e).

    2. I could buy a second generic power supply and basically do the same thing - connect it to a common ground with the original, have them both switch on together, and again use the new PSU to power the graphics card. I've never done this before, but I should be able to manage it, PROVIDED I can be sure that I'm using the correct wires from my old PDP-121P unit. Since I don't have the wiring specs, this approach also might not work.


    Any thoughts on how I might proceed?

  2. #2

    clever PSU workaround needed

    I would do the second option. There is a tutorial somewhere on how to link up two PSU's so they start up and shut down at the same time. A lot of people who do WCing do this. I'll look around for it later tonight on google and see if I can find it.

  3. #3
    Master Modder Tazz's Avatar
    Join Date
    Feb 2006
    Posts
    1,587

    clever PSU workaround needed

    http://www.pcguide.com/vb/showthread.php?t=42045

    Midway down shows the pinout for your PSU vs a standard ATX PSU, I would verify that the wire colors match yours and then do some voltage measurements on your PSU.

    I had this issue on a HP with a MSI board years ago. There are a few color differences there, depending on the voltages on your PSU, it might be possible to convert a standard PSU over. From what searching I have done, I havent found anyone that has accomplished this.

  4. #4
    Clear Coat
    Join Date
    Jul 2006
    Posts
    878

    clever PSU workaround needed

    So, our AGP card has a molex connector on the video card itself? I would also choose the second power supply option.

    Article:
    http://pc-mod.com/articles/atx/

    Useful Wiring Diagram:
    http://pc-mod.com/articles/atx/atx5.jpg

    Edit:
    On the more powerful supply, splice wires onto the green and black wires (mentioned in links above) before the connector, then plug the connector into the mobo. On the secondary PS, you can just insert the spliced wires into the correct socket in the connector.

  5. #5
    Clear Coat
    Join Date
    Jul 2006
    Posts
    878

    clever PSU workaround needed

    Oops, i forgot that you have a proprietary supply.
    To find the equivilant of the Green "standby" wire, you should take the PS out of the computer case, and plug it into the wall. Then whip out your handy digital multimeter, and randomly start testing all of the colored wires connecting them to the (+) or red Probe, and just the other (-) or Black probe connected to one of the black wires. If the Power supply does not have colored wires, you have to just randomly testing wires until you find a pair that reads about 5v. The positive wire is the Green wire, and the negative is the ground (black).

    All of the above^^ assumes that the Compaq Power supply merely has rearranged wires rather than completly different technology. Also if the wires arent colored ygou seriously should consider getting a new PS and Mobo. You should be able to find a cheap 754 pin motherboard for much less than $100, and then all you would need is a better PS, and some TIM (like Arctic Silver 5/7 or w/e). Or, if your processor is the older socket A model, then you might be able to salvage an ATX mobo out of a local computer repair store for cheap.

  6. #6

    clever PSU workaround needed

    Wow, good responses guys! Some really helpful info here.

    The link provided by Tazz really nails the issue of the PSU wiring. The colours of my wires are identical to those of the Compaq diagram. And although they are completely different to standard ATX colours, it's clear from the rest of the discussion that the 20-pin connector is basically the same as the ATX standard. This is confirmed in some other threads I found today:

    http://www.xtremepccentral.com/forums/showthread.php?t=11199&goto=nextoldest
    http://forum.pcstats.com/showthread.php?t=33902

    The proprietary bit actually has to do with a different connector, a 2-pin male connector on the motherboard which powers the CPU fan. In the first link above, the OP finds he can use a 3-pin female connector that comes with his Antec PSU. I wish I knew what that 3-pin cable is called, so that I could look for a PSU that comes with one. In Tazz's link, the OP talks about modifying a standard power cable, but in the end sticks with his proprietary PSU.

    I reckon the best thing would be to buy a standard ATX power supply. I'm thinking about the Antec TruePower 550W, which should be more than enough for my modest setup. If I can swap the PSUs and get the CPU fan working, then great. Failing that, I've now got all the information I need to attempt the dual PSU arrangement that fusinfun talks about.

    Thanks a lot guys, you've already been most helpful! Is there anything I've missed? Any particular cable that might come as standard in modern PSUs and which could easily be made to fit the special 2-pin CPU fan connector?

  7. #7
    Master Modder Tazz's Avatar
    Join Date
    Feb 2006
    Posts
    1,587

    clever PSU workaround needed

    Is there in fact a P9 connector coming off the stock PSU? Without having a mobo and PSU like yours its just speculations. If in fact the stock PSU does have the P9 connector, check the voltage on that connector. You should be able to pigtail off of one of the other wires for a power source and use a standard P9 connector off just about any 3 prong pan pigtail to make the connection.

    Provide pictures of the 20pin connector and the 2 pin they are talking about if you can. Of your working system.

  8. #8
    Wet Sanded
    Join Date
    Aug 2006
    Posts
    752

    clever PSU workaround needed

    I didn't read each and every reply, so forgive me if someone has said this..

    Take a multimeter and find the voltages of the pins, and wire a standard atx psu to to respective places.

  9. #9

    clever PSU workaround needed

    Is there in fact a P9 connector coming off the stock PSU? Without having a mobo and PSU like yours its just speculations. If in fact the stock PSU does have the P9 connector, check the voltage on that connector. You should be able to pigtail off of one of the other wires for a power source and use a standard P9 connector off just about any 3 prong pan pigtail to make the connection.

    Provide pictures of the 20pin connector and the 2 pin they are talking about if you can. Of your working system.
    Okay, I'm not really equiped to take photos or voltage measurements at this moment in time. I shall try to borrow a camera and multimeter. All I can do for now is provide some description.

    My Compaq PSU has the following connector cables, apart from the Molex connectors:

    - A 20 pin main power connector. Apart from different coloured wires, this looks like any picture of a standard ATX 20-pin connector.
    - A square 4-pin connector (plugged in just above the AGP socket, quite close to the back panel), labelled as P3.
    - A 4-pin connector (not plugged in), labelled P8
    - A 2-pin connector (plugged in between the RAM banks and 20-pin connector, quite close to the front panel), labelled P9.

    It seems pretty likely that this last one is the proprietary one talked about in those other threads. The best way to describe it is that it looks like a capped jumper, except that there's two wires coming out of it. The two wires are white/red and white/blue.

    I thought that P8 and P9 are only used in AT specification boards, and had assumed that these were being used as convenient labels by Compaq to designate their non-standard connectors. But then you talk about a standard P9 connector, so maybe I've got that wrong.

  10. #10
    Master Modder Tazz's Avatar
    Join Date
    Feb 2006
    Posts
    1,587

    clever PSU workaround needed

    I cant find a pic right off showing the P9 label. The plug is that of a 3 pin fan connector, I have had several labeled as P9 and that is what I am talking about. I do believe the AT style P9 is a wider flat plug.

Page 1 of 3 123 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. funky 5.25 drivebay filler needed?
    By thequeenscheese in forum Resource Database
    Replies: 2
    Last Post: 07-12-2013, 03:24 AM
  2. Questions needed for Podcast 23!
    By Dewayne in forum Podcast
    Replies: 19
    Last Post: 10-04-2011, 02:08 PM
  3. Water-cooling advice needed!
    By ChrisChurchill in forum Modding Questions
    Replies: 4
    Last Post: 05-02-2011, 06:02 PM
  4. Halp! (Career advice needed)
    By Doomzilla in forum Talk Freely
    Replies: 9
    Last Post: 01-11-2008, 03:02 PM
  5. Lil bit o' help needed
    By Assassin in forum Talk Freely
    Replies: 3
    Last Post: 10-08-2006, 08:02 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •