Question about HP Pavilion A635W PC Desktop

2 Answers

I hadn't turned my hp Pavilion a635w desktop off for some time but, I decided to turn it off before I left for Colorado. I was gone for a week. When I got home I tried to turn the PC on and it wouldn't. Finding out my power supply was no good. So I replaced it and when I powered the PC up it showed a screen that I believe was the BIOS screen. It showed specs in the computer. All the info was in a off white color but, in bright white there was a message that read no system clock DDR3 I think. So I was told to replace the battery on the motherboard witch I did. After I did that the PC powers up but, the monitor won't display anything. I tried unplugging the monitor for 30 seconds and still no display. So I tried the monitor on another PC I have and the monitor worked fine. So I know it's not the monitor with the problem. The problem lies in the PC. So with what I've tried to explain. I was hoping you can help pin point the problem with my PC.

Posted by on


2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • HP Master
  • 5,660 Answers

1) There is a such thing as a bad Power Supply. New or not.

2) You may not have all required power cables plugged in.

Besides the ATX main power cable, there is also a 4-pin ATX +12 Volt power cable, that has to be plugged into the motherboard.

This cable,

This is HP Support, and the Motherboard Specifications page,

I would like you to scroll down to the illustration of the motherboard.
To the left of VIA KM400A is a small square. To the top of the small square is printed ATX12V
This is where the 4-pin ATX +12 Volt power cable plugs into.

(The motherboard chipset is the Northbridge chip, and the Southbridge chip.
The VIA KM400A chip is the Northbridge chip. Should be under an aluminum finned Heatsink)

I would also like you to clear CMOS Error codes.
Computer unplugged from power press the Power On button, and hold it in.

Hold it in for a count of 5 seconds. (And I mean at least 5)
Let go of the Power On button.
Do this procedure 2 more times.

This action will clear CMOS Error codes, and reset BIOS back to the factory default settings.
Plug the computer back into power. WAIT 1 minute, then turn the computer on.

Be sure ALL power cables are plugged in, and plugged in tightly.

A) ATX main power cable. (20-pin ATX main power cable)

B) 4-pin ATX +12 Volt power cable

C) All 4-pin standard Peripheral power cables.
1 is for the Harddrive.
1 is for the CD or DVD optical drive, ( Or 2 if more than 1 optical drive)
1 may be used in conjunction with an adapter cable, and used for power to a computer case fan.

3) Make sure the ram memory module/s are seated in tightly. (Module = 'Stick')

You may wish to clean the gold plated contact pins on each ram memory module.
The gold plated contact pins develop corrosion.

Computer unplugged, and you have followed Anti-Static Precautions, remove each ram memory module.
Use a pencil eraser to clean each contact 'strip'.
If you use an eraser on the end of a pencil, refrain from letting the metal band contact the contact pins.
Just takes a few strokes of the eraser on each contact pin.

After you have finished cleaning a contact strip it may look as though you have done nothing at all
I assure you that you have. Doesn't take much corrosion to make a bad contact.
Use air to remove the eraser dust before you reinstall the ram memory.
If air from a can of compressed air for computers is not available, air pressure from your mouth is sufficient.

If this doesn't solve the problem please post back in a Comment.
We will go on to test the various voltages coming out of the Power Supply.

(If a multimeter is not available an economical unit can be purchased. Most auto parts stores carry them, as well as a multitude of other stores. A $5 to $20 unit will do just fine.

The voltages involved are 3.3 Volts, 5 Volts, and 12 Volts.
ALL are DC voltage.

Two D cell flashlight batteries produce 3 Volts DC )


Posted on May 29, 2011

  • 2 more comments 
  • joecoolvette
    joecoolvette May 30, 2011

    Thank you for the rating most kind!

  • Josh Heilman Jun 02, 2011

    I have tried your suggestions and I'm still not receiving power to the VGA connection. I also tried putting a new memory module and no luck.

    Thanks Again,

  • joecoolvette
    joecoolvette Jun 03, 2011

    Thank you for updating your progress. (Or lack of at the minute. It's okay, read on)

    Some questions I need to ask;


    1) I need to know that all of the required power cables from the PSU (Power Supply Unit) are connected up, and connected tightly.

    A) The 20-pin ATX main power cable.
    Down in tight until the lock snaps over the tab. (Female connector on motherboard has the tab)

    B) The 4-pin ATX +12 Volt power cable.
    Same as above.

    C) The 4-pin standard Peripheral power cable, (Molex), plugged into the back of the 80GB IDE (PATA) harddrive.

    D) The 4-pin standard Peripheral power cable to your optical drive. (It's an IDE unit also. CD/DVD drive)

    Answer is yes to All of the above?
    I need to know that the PSU is a good unit. Not a bad unit with a weak voltage power rail.
    If you do not have a multimeter an economical unit cab be purchased for around $5 to $10.

    There are three voltages I would like you to check coming from the new PSU.
    1) The 3.3 Volt power rail
    2) The 5 Volt power rail.
    3) The 12 Volt power rail.

    ALL Orange wires coming from the PSU are 3.3 Volts. (All DC voltage)
    ALL Red wires are 5 Volts.
    ALL Yellow wires are 12 Volts.
    ALL Black wires are Ground wires.

    (Again, two D cell flashlight batteries produce 3.3 Volts. { DC } This is the voltage you will be dealing with. Very low. High voltage { AC} comes into the PSU, but is lowered down to the above stated low DC voltages. These low voltages are what the computer uses)

    Multimeter's vary.
    The Red probe lead is the Positive lead.
    The Black probe lead is the Negative lead.
    Set the multimeter's Function knob to DC voltage.
    If there is a scale range also set it to the 0 - 50 Volts scale.

    The Positive (Red) lead goes to the power wire. Orange, Red, or Yellow.
    The Negative (Black) lead goes to ANY Black wire you see. ALL are Ground wires.

    Computer plugged into power, power button pressed on;
    Place the Positive probe lead down into the back of any connector with a Red wire. (5 Volts)
    For an example let's use a 4-pin standard Peripheral power cable,

    The photo to the far right shows the back of the connector. The probe lead goes down into the back of the connector, into the socket hole with the Red wire.

    The probe lead must go down into the socket hole pretty far. (3/8th's Inch?)
    The probe lead must touch a metal terminal.
    (At the end of every wire in a connector is a metal terminal. The probe lead must touch that metal terminal)

    Place the Negative probe lead into the socket hole with a Black wire.
    Scale read 5 Volts or very close to it?

    Do the same for the Yellow wire. (12 Volts)
    (11 to 13? OK. Less than 11? No good)

    PSU checks out?

    At this point I need you to run a visual test.
    Need to know if there are obvious signs of damage to the motherboard.
    With your being gone, and assuming the computer was left plugged into power, and the Ethernet cable still attached, I need you to check to see if an electrical spike may have caused damage.

    Computer unplugged from power, computer case open, flashlight in hand;
    Check the Electrolytic Capacitors on the motherboard. They may, or may not show obvious signs of damage.


    Post back we'll go on form there.
    Regards joecoolvette

  • joecoolvette
    joecoolvette Jun 03, 2011

    Edit: "We'll go on FROM there." (I'm going to have to fire my proofreader. Wait a minute! That's me! lol!)


  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.


    An expert whose answer got voted for 20 times.


    An expert who has answered 20 questions.

  • Expert
  • 106 Answers

More than likely you have accidentally unseated your video card open the box and press the video card tightly into the pci slot.

don't forget to give testimonial and the votes 4 thumbs up if I helped.

Posted on May 29, 2011


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

My cd drive don't wont to burn CDs

maybe you need to update the drivers for it

have you try that yet?

Oct 01, 2012 | HP Pavilion A635W PC Desktop

1 Answer

How can i enter into Bios of HP Pavilion a730n desktop PC.I mean by pressing which key?

press f10 for bios . about 3-5 seconds after turning it on. you may tap it several times.

hope this helps

Don't forget to vote for me
Thank You

Jul 14, 2011 | HP Pavilion A730N (PJ510AA) PC Desktop

1 Answer

My compaq presario sr2010nx desktop won't turn on. I tried fooling with the off/on switch wiring and it came on for a short time. All was well. I hadn't used it for a week and tried to turn it...


Sounds more like a power supply problem. First test the on/off switch by tracing the wires to where it connects to the mother board. The plug is usually marked "pwr sw" . Unplug the wire from the board & short out the 2 pins where the switch was plugged in using a small screw driver or any other conductive material. If the pc still fails to turn on, try replacing the power supply.
Best wishes,

May 10, 2011 | HP Compaq Presario SR2010NX PC Desktop

1 Answer

Unpacked computer after move moniter will not stay on it comes on and says going to sleep shuts off please help

please check the cable between the computer tower and the monitor.
either the cable is not connected properly or the cable is defective.
this is a message you normally get when the computer is off, and you try turning on the monitor alone.

hope it helps

Sep 24, 2010 | HP Pavilion A635W PC Desktop

1 Answer

I have a hp pavilion a635w that will not boot up not even to bios

check if the ram if is compatible with the board
check if the battary power the bios

Dec 22, 2009 | HP Pavilion A635W PC Desktop

1 Answer

Hp pavilion not turning on

try to remove the battery and plug the system in with no battery and try to turn it on if this does not work put the battery back in and turn on hold the on button in for 5sec and should turn on if not could be a problem with a power surge when you was gone and the M/B got messed up

if the power supply is ok that is make sure when pluged in the light comes on so you know you have power

Nov 01, 2008 | HP Pavilion dv1000 Notebook

1 Answer

Motherboard problem for a 754 socket

I found this replacement motherboard with a simple google search:

Jun 25, 2008 | ASUS A7V8X Motherboard

1 Answer

Pavilion a635w motherboard problem

Hi HotOlds, you did not hurt the motherboard. You did not install the memory correctly. Take the old memory & look at the contacts on the DIMM. There is a notch there & a notch in the memory slot. These two notches must be matched up when inserted. Each memory slot has a locking tab at each end of the slot. When you insert the memory correctly the locking tabs snap closed ensuring the memory will not come out. The beeps you are hearing are telling you the memory is not seated correctly. Same for the memory you bought. However, the memory you did buy must match the memory for the Pavilion A635W. This link will show memory you can use for the Pavilion A635W motherboard.
(Buying a new board).
The link you have posted for the ECS Gf6100-M754 MB. Will not take the memory you currently have. You will have to buy DDR3 memory but that is not the main issue. If you intend to put this motherboard into the Pavilion case it may not fit. Measure the board in the HP & check the dimensions of the ECS board you want to buy. You will have to buy a new CPU as well. The HP uses an AMD CPU & the ECS uses an Intel CPU. Basically you will be buying a whole new system including the CPU & memory, which may not fit in the HP case. You will also need a higher power supply to run the ECS board. HP's power supplies are much smaller.

Good Luck!
I will not be online here at fixya for the next week or so.

Jun 25, 2008 | ASUS A7V8X Motherboard

1 Answer

Replacing Motherboard with combo

You can just replace your video card. If your using the Hp A635w with the intergrated video it may have just died. You sill have a free AGP slot on the board. Buy a AGP card with DDR2 or DDR3, change the bios setting to boot to the AGP card first & Bingo! Your up & running. The HP A635w is a Micro-ATX form factor: 9.6 inches x 9.6 inches. Thats the board size & that is what you'll need to fit that HP case. Micro-ATX's limit you CPU type & speed. Like dual core's.
I've listed one board combo doing a quick search & this board will take your current memory & fit the HP case.
As I mentioned you can go for the AGP card listed in this link. Six pages of AGP's.
It's up too you pick your flavor. Enjoy!
please vote...

Feb 16, 2008 | ASUS A7V8X Motherboard

Not finding what you are looking for?
HP Pavilion A635W  PC Desktop Logo

134 people viewed this question

Ask a Question

Usually answered in minutes!

Top HP Computers & Internet Experts

Les Dickinson
Les Dickinson

Level 3 Expert

18394 Answers

Doctor PC
Doctor PC

Level 3 Expert

7733 Answers


Level 3 Expert

2600 Answers

Are you a HP Computer and Internet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides