Video Card / Motherboard Works Intermittently

Normally, I'd be inclined to believe that the PSU would be the next likely culprit, but because this is an HP system (notoriously known for mobo trouble), I'd venture to say mobo.

Still, you should check the usual suspects: RAM, PSU, CPU, etc. Double check that all the wiring is snug. Test your RAM with MemTest86+ v4.2 . Test the voltages on the PSU P1 connector. Warning: Removing the side panel can sometimes void warranty, so check with HP before opening the case.

If im not mistaken the computer wouldn't boot if their were any bad sticks of Ram, and as I said in the first post the computer works fine after turning it on and off a few times. And for testing the PSU im not I want to get into that yet. I have check all of the connections and they seem fine. And something else to note is that the GPU fan spins even when it wont boot,.

You're partially correct. Intermittent problems are rather difficult to diagnose, as the problem is inconsistent. Even harder to work with is a prebuilt system that has warranty attached; you don't want to do anything that will void the warranty.

From personal experience, I can tell you that I had intermittent "no display" issues. I tested the RAM the I had orginally purchased for my custom/home-build system. The results were inconclusive. One test showed the RAM had errors, another test passed with flying colors. I decided to replace the RAM anyway (Newegg had a sale on RAM).

After installing the new RAM the computer appeared to return to proper operation. When the problem started again, I tested my PSU. The voltages were within tolerable levels. Thinking that the mobo was going bad, I pulled out the RAM sticks to find out if the mobo speaker would beep. It did, which meant mobo is good. After reinstalling the new set of RAM, the computer has been running smoothly since.

The point of this is that my RAM is in fact perfectly fine, but I still had the intermittent "no display" because it may not have been seated well enough. So, testing your RAM with MT86+ will help you determine if there are any errors with the RAM. If there are, consider returning the computer or contacting HP for replacements.

Thanks for responding so quickly,

My computer has been out of warranty for almost six months so no problem there, i will test it with MemTest86, and post back later with results, ill also check my mem, to see if its properly seated. Not sure if it matters but, the on board works flawlessly with out any boot problems.

Thanks,

Ryan

I ran MemTest86 with no errors, im not sure what to try now besides testing the PSU,

Thanks for the help.

PSU is the next step. To test it, use a digital multimeter and switch the dial to VDC. The black probe can either be stuck behind any of the black wires on the P1 connector, or touch it against anything bare metal on the case. As for the red probe, touch it against the back of the following wires and compare the corresponding voltages:

Red: +5V
Yellow: +12V
Orange +3.3V
Blue: -12V
Brown: +3.3V
Green: +5V
Gray: 0 to +5V - 0 when off, up to +5 immediately after turning the power switch on

Note: Power to the motherboard must be present in order for you to properly read the voltages on the P1 connector. An acceptable variance of 5-10% is considered normal.

Well I don't have a digital multi-meter, but it still doesn't make sense how after a few restarts it will work fine for hours on end, it seems that the computer would crash, or have other issues if the Mobo isn't getting regular power.

Thanks again,

Ryan

That's a symptom of an intermittent short. Anything electrical can exhibit these symptoms, the trick is narrowing it down to the component that is causing the short. The places I've found shorts are:

1. PSU - frayed wire somewhere that somehow touches bare metal
2. mobo - the CPU socket back plate may have insufficient clearance between mobo and case; standoffs may be insecurely fastened; one or more of the fan headers
3. Front panel - sometimes the power or reset switch has a short that causes boot problems

To eliminate these possibilites, breadboard your system. To accomplish this:

1. Disconnect/Remove everything from the mobo, except for CPU and HSF
2. Remove mobo from case, and then place it on a non-conductive surface (wood, cardboard, etc)
3. Reconnect the PSU to the mobo, and don't forget about the CPU (P4) connector
4. Install just one stick of RAM
5. Connect the monitor to the mobo
6. Jump the PWR_SW pins with a flathead screwdriver, or similar tool

After performing these steps, you should get a display. POST will result with an error indicating that no HDD could be found, or no bootable device attached. If this is what you experience, simply turn off the power to the system by jumping the PWR_SW pins again.

Next, install the GPU and connect the monitor. Power up the system again by jumping the PWR_SW pins. If you get a display and the error message about a missing HDD, shut down and then attach the front panel connector to the mobo. Press the power button to turn on the system.

Again, if you get a display and the error message about the HDD, shut down. Now install the HDD and power up again. If the system boots into Windows, you've likely got a short between mobo and case.

Hi Again,

Yesterday I went in and checked all of the connections and re seated the ram, now it seems to be working. I have booted about ten times without any problems, hopefully it will stay this way.

Thanks for all of the help