Motherboard shopping

[blu at vl.com (Tom Metro)]

markw at mohawksoft.com wrote:
> 1st, with a good volt meter, while the machine is running, make sure all
> the voltages are good. Sometimes people add cards and hard disks to
> systems and overload the power supply and push the voltage down to where
> the system sort of runs.

This is a good idea, though with an intermittent problem it probably 
wont rule anything in or out as the cause. Making sure all the supply 
voltages are within 10%, or preferably 5%, of their ratings is a good 
check, but beyond that unless you know what your motherboard happens to 
tolerate it may not mean much.

Similarly, you can buy power supply testers fairly cheaply these days 
that will check the voltages under load, but without a load specifically 
sized to test your supply (or matching the requirements of your 
motherboard and peripherals), it'll only tell you whether the supply is 
generally functioning OK.

You might want to try selectively adding and removing various high 
current peripherals (drives, video card) and see what the voltages are 
after powering up and letting things stabilize. If there's more than 5% 
change in any of the voltages, you're probably hitting the limits of the 
power supply.

If this is a home built system, it also might be a good idea to compare 
the rated wattage of your supply's 12 volt output (not the wattage of 
the entire supply) to the wattage requirements of your CPU. Many older 
supplies have high wattage ratings, but inadequate current on the 12 
volt line to run the latest CPUs. (Motherboards have on-board regulators 
that draw on the 12 V line to generate the CPU supply voltage.)


> ...take out half the RAM. See if it still a
> problem. If it is not, replace the first half of the RAM with the half
> that was removed and see if the problem returns. If it does, one of those
> two ram sims/dims are the problem.

This is also a good tip, and particularly handy if you don't have 
another system you can borrow some known working RAM from. I've used 
this technique on a number of occasions.

  -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/