How do I check 3.3v on power supply?

[RockDog]

Hi,

I'm working on an old Compaq system for the 3rd time. I did a fresh install of Win98 the first 2 times. Both times the system ran perfectly until I sent it off with it's owner. Within a few days he would experience Illegal Operations, BSODs and lock-ups. After the second time I suggested to the owner that he get an UPS. He bought a Belkin that had monitoring software and noticed that the incoming voltage would drop as low as 110V.

The plan was to reformat and install Win98 one more time and hopefully all would be good. Well, so far this 3rd time around I've had one BSOD during the install of Win98 and 2 illegal operations shortly after.

I was suspecting that the power supply may be bad so I checked the 5V and 12V with my voltmeter.

Plugged into Antec Power Supply Tester
12V=11.89
5V=4.97
3.3=3.27

Idle
12V=11.73
5V=4.97

100% CPU Load
12=11.57
5V=5.05

Under 100% CPU load it seems to me that 11.57 is pretty low. I was wondering if there was any way to check the 3.3V while the system was running? Or is there any way to calculate it given the other 2 values?

Thank you,
RockDog

 

[majewski9]

Those are perfectly acceptable values. In fact I bet you that sometimes you could find the 12 volt line putting out less than 11 volts. 12 volts is just a value and it is rediculous to assume that your supply will put out a continous 12 volts. I dont think it is your power supply!