Enermax Coolergiant PSU +5v low???


Jul 24, 2004
quote 1

PSU, UPS & Power FAQ

Q2. OK... So whats the easiest way to diagnose that ive got a bad PSU?

2. Run a system monitoring program like Motherboard Monitor 5. Watch the voltage rails, especially the 5v rail for AMD

systems and teh 12V rail for P4 systems. They should be within 5% of optimal, and they shouldnt fluctuate or drop

significantly when the cpu goes from idle to full load. If your voltages are very low or high or fluctuate they your PSU is

in trouble.

quote 2

07. The most important factors of a good power supply are a clean non fluctuating current, and a low variation in voltage.

The voltage in a stable system is usually tolerant to roughly 1 to 3 percent of the average voltage. For an example-

3.3 volt rail-3.13 volts 5.4 percent deviation
5 volt rail-4.78 volts 4.6 percent deviation
12 volt rail-11.23 volts 6.9 percent deviation

While these voltages aren't too terrible, they are also erratic enough to cause system instability.

3.3 volt rail-3.25 volts 1.5 percent deviation
5 volt rail-4.98 volts .4 percent deviation
12 volt rail-11.78 volts 1.8 percent deviation

These voltages are much closer to a systems reasonable tolerance


I bought yesterday an Enermax Coolergiant 430w PSU http://www.coolergiant.com/products/power_supplies/coolergiant_ax_series.html , both MBM and bios are showing my +5v rail at 4.91v (idle). Under load (cpu burn in, prime95), the rail is holding rock steady at 4.83v and the hi/low log on MBM and webtemp is showing from 4.83-4.91, with an average of 4.88v. The +3.3 and +12 rails are freezed at 3.31v and 12.2v even under load. By the way, vcore dropped from 1.75v to 1.68-1.69v. I have no multimeter so i can't verify the exact values.

I know anything within +/- 5% is fine, but its an Enermax and not a cheapo noname thing, so why is only the +5v rail
fluctating so much??? Should i return it???

Enermax Coolergiant 430w
Cooler Master ATC 210 & 2*YS Tech Fans
MSI K7T Turbo
2*Samsung RAM
Athlon XP 1700+
Swiftech MCX 462 & Noiseblocker S4 Fan
ATI Radeon 9500 Pro
Spire Exhauster
Adaptech 29160 SCSI
BM Ultrastar HDD
IBM Deskstar HDD
Sony DRU 700a DVDRW
3Com 3c905c-TX-M NIC


Mar 18, 2004
Those numbers are jsut fine. On my Enermax, happens to be the 5 that's rock steady,a nd 12 and 3.3 that fluctuate a little bit, but never enough to cause problems, and yours aren't enough to cause problems either. Don't worry about it.