system rebuild-no video

I just finished rebuilding my primary system (sucessfully). Am now working on the secondary. i was concerned about the MB of this system and when I reconnected all I received no video signal. I tried connecting a different video card (PCI) and received same result. The first first was an AGP. How can I deduce whether I have a MB or video card failure here? Currently I assume the MB is bad based on 2 different card types tried (AGP/PCI).
ISSUE: No video signal
KX600 Pro Via chipset
Radeon 9550 AGP
AMD Sempron 2.2ghz cpu
512 DDR 184-pin ram (unknown specs)

?????
Any suggestion welcome.

 

The KX600 Pro Via chipset is not new so I assume that motherboard is not either. Do you know for a fact this motherboard was still good? How about the CPU and RAM? Where did they come from? If this motherboard has on-board graphics, try it.

Any beeps?

Did this motherboard ever work while mounted in that case? If you just installed it, are you TWO hundred percent sure you do not have an extra case standoff under the motherboard? That is, are you sure each standoff is located directly under a corresponding motherboard mounting hole? Since cases support 1000s of motherboards, there are always more standoff holes than there are motherboard mounting holes. If one is under there, it could be shorting out the motherboard - and may cause, or have caused, permanent damage.

If not 200% sure, while observing ESD precautions, pull the board and set it up on a flat, non-conductive surface. Connect the monitor, 1 stick of RAM, PS/2 keyboard - a [good] power supply and that's it - no drives. Then very carefully, short the two pins that connect to the front panel power switch for 1 second to start the computer. You should see the boot process start, then freeze when it cannot find a boot drive.

If sure nothing (including loose screws) is under the motherboard, first thing I always want to ensure is good, clean power. So I swap in a PSU I know is good.

 

Well went thru more T/S stripped the system down to PSU, MB, RAM, Video Card, and mouse/keyboard. System booted into bios successfully. Add HDD and DVD drive and... powers up but no video or bios. I am using a generic 350 watt PSU that has worked for several years on the previous build. That build was a socket 462 board with an AMD 1900+ CPU, other hardware is the same. I changed out for a socket 754 MB with an AMD Sempron 3300+ CPU. That is the only difference in the 2 setups. Oh, other than the RAM but I'm only trying to use one stick of 512MB PC3200. Observing the "Vcore" display in bios it appeared that the PSU was barely supplying enough juice to run the barebones setup assuming I was reading it correctly. Granted, this was a cheaper PSU that I bought way back but it worked perfectly so I assumed it was ok but it looks like it might be the culprit here. Anyone able to confirm my suspicions? I know the HDD and DVD drive are in decent working condition as I used them regularly with the old build. Therefore, I assume that by adding the 2 devices I am over taxing the PSU??

 

Then add one at time. One of these devices may be bad, pulling down the PSU so it is not able to run everything else. These devices use 12V to spin up. 12V is also used for the graphics.

Also note that 350W is on the small side. Also note that power supplies get weaker, and less efficient over time - they age.

How do you know? What was it? vCore voltage typically run around 1.5V +/- .3V. vCore voltage is determined by many factors - not just the PSU. The PSU supplies only 3.3, 5, and 12V. Those 3 voltages are what must be, and must have sufficient current behind them to produce the needed watts. And finally, it is these voltages that must be stable keep a system happy.

I use a FrozenCPU Ultimate PSU Tester for power supply (PSU) testing when I am away from home. It is not as good as a qualified technician testing the PSU under a "true" (realistic) load with an oscilloscope or power analyzer, but close. The advantage of this model is that it has an LCD readout of the voltage. With an actual voltage readout, you can better detect a "failing" PSU, or one barely within specified tolerances. Lesser models use LEDs to indicate the voltage is just within some "range". These are less informative, considerably cheaper, but still useful for detecting PSUs that have already "failed". Newegg has several testers to choose from. All these testers contain a "dummy load" to fool the PSU into thinking it is connected to a motherboard, and therefore allows the PSU to power on, if able, without being attached to a motherboard - great for testing fans, but again, not a true load. Alternatively, you can swap out the PSU with a known good one that meets the computer's power requirements.

I do not recommend using a multimeter to test power supplies. To do it properly, that is, under a realistic load, the voltages on all the pins must be measured while the PSU is attached to the motherboard and the computer powered on. This then requires poking (with some considerable force) two, hard and sharp, highly conductive, meter probes into the heart of the computer. One tiny slip can destroy the motherboard, and everything plugged into it.

Use the eXtreme PSU Calculator Lite to determine your power supply unit (PSU) requirements. Plug in all the hardware you think you might have in 2 or 3 years (extra drives, bigger or 2nd video card, more RAM, etc.). Be sure to read and heed the notes at the bottom of the page. I recommend setting Capacitor Aging to 30%, and if you participate in distributive computing projects (e.g. BOINC or Folding@Home), I recommend setting TDP to 100%. Research your video card and pay particular attention to the power supply requirements for your card listed on your video card maker's website. If not listed, check a comparable card (same graphics engine and RAM) from a different maker. The key specifications, in order of importance are:

1. Current (amperage or amps) on the +12V rail,
2. Efficiency,
3. Total wattage.

Then look for power supply brands listed under the "Good" column of PC Mechanic's PSU Reference List. Ensure the supplied amperage on the +12V rails of your chosen PSU meets the requirements of your video card. Don't try to save a few dollars by getting a cheap supply. Digital electronics, including CPUs, RAM, and today's advanced graphics cards, need clean, stable power. A good, well chosen supply will provide years of service and upgrade wiggle room. I strongly recommend you pick a supply with an efficiency rating equal to, or greater than 80%. Look for the 80 Plus - EnergyStar Compliant label. And don't forget to budget for a good UPS with AVR (automatic voltage regulation).

As I mentioned above, "first thing I always want to ensure is good, clean power. So I swap in a PSU I know is good."