[SOLVED] Upgraded from 300W generic to 600W Coolermaster but voltages still low?

Brogden Fields · 04-23-2008, 04:34 AM

I have an Athlon XP 2400+ on a PC Chips M848A motherboard that I built some time ago. Over the years it has accumulated stuff so that there is now 2GB RAM, 60GB and 40GB hard drives, NVIDIA GeForce FX 5200 (256MB) with two 19" monitors attached, DVD reader and CD rewriter, 2 x USB 2.0 PCI cards, 3 x printers, scanner, 500GB USB external drive. I don't play games, and it is not overclocked so the CPU is running at 2GHz and the RAM at 200MHz.

I noticed that the voltages looked low. The +3.3V was showing 2.26V and the +5.00V showing 3.44V, and all the other voltages looked out, as shown in the first screen grab. So I used an online calculator to check my power supply requirements. This worked out at about 350W including a 30% margin for surge power. I decided I needed some more power and got a Cooler Master "Green Power" 600W supply rated at 600W continuous, 700W surge and up to 85% efficiency. After I installed this I eagerly checked and what do you know, the voltages didn't look any better than before, as shown in the second screen grab. In fact, they look worse:

Generic Coolermaster
CPU Core 1.60 1.60
+2.5V 2.51 2.48
+3.3V 2.26 2.05
+5V 3.44 2.17
+12V 8.97 3.87
-12V -6.53 -5.10

This wasn't what I was expecting. Is the Coolermaster faulty, or do I need yet more power, or were the voltages that I was getting from my generic 300W PSU OK and I have wasted my money on the Coolermaster?

Thanks for any help - Brogden

Tumbleweed36 · 04-23-2008, 05:11 AM

Quite possibly, your motherboard has some sensor problems. That is quite common, so if you don't have any issues like it shutting down, don't worry about it, because it could not work with some of those listed voltages. I would give a quick check to see what the bios reports as the voltages and temps and let's compare that to what you are seeing, because some computer motherboards don't report well with some programs and the bios is normall the most accurate.

**Terrister** · 04-23-2008, 04:08 PM

See if you see voltages listed in the bios. This is the best way to check a machine if it is there.

Jebtall · 04-23-2008, 09:11 PM

You can't trust software to give you an accurate voltage reading. Bios will be better, but not necessarily the correct voltage either.

To truly see what voltage you have you need a voltmeter. While the PC is running, check the 12V and 5V rail at a free molex connector (the connector that goes to you dvd or hd). The 3.3V is a bit tricky, but if your 12V and 5V rail are ok, your 3.3V is probably ok, especially if you aren't having any problems.

If you don't have a voltmeter, you can buy an inexpensive one at Sears, or you can buy a decent PSU tester for about $20.

Brogden Fields · 04-24-2008, 04:01 AM

OK, well I have an analogue AVO, and a DVM, but not the brains to use them obviously! The yellow wire on the Molex is giving a rock steady 12.50V +/- 0.01V, and the red wire 4.81V +/- 0.01V. At the same time, the Mother Board Monitor dashboard is showing the 12V supply as ranging 8.65V - 3.55V, and the 5V ranging 3.82V - 2.52V. And as Jetball pointed out, I am not having any problems. Next step is to uninstall MBM and stop worrying about problems I haven't got. Thanks guys!

04-23-2008, 05:11 AM	#2 (permalink)
Tumbleweed36 Asst Manager Hardware Join Date: May 2005 Location: USA Posts: 14,802 OS: XP Professional	Re: Upgraded from 300W generic to 600W Coolermaster but voltages still low? Quite possibly, your motherboard has some sensor problems. That is quite common, so if you don't have any issues like it shutting down, don't worry about it, because it could not work with some of those listed voltages. I would give a quick check to see what the bios reports as the voltages and temps and let's compare that to what you are seeing, because some computer motherboards don't report well with some programs and the bios is normall the most accurate. __________________ ----------

04-23-2008, 04:08 PM	#3 (permalink)
Terrister Moderator Hardware Forum Join Date: Apr 2005 Location: West Georgia, USA Posts: 6,914 OS: Xp	Re: Upgraded from 300W generic to 600W Coolermaster but voltages still low? See if you see voltages listed in the bios. This is the best way to check a machine if it is there. __________________

04-23-2008, 09:11 PM	#4 (permalink)
Jebtall Registered User Join Date: Feb 2008 Posts: 52 OS: xp	Re: Upgraded from 300W generic to 600W Coolermaster but voltages still low? You can't trust software to give you an accurate voltage reading. Bios will be better, but not necessarily the correct voltage either. To truly see what voltage you have you need a voltmeter. While the PC is running, check the 12V and 5V rail at a free molex connector (the connector that goes to you dvd or hd). The 3.3V is a bit tricky, but if your 12V and 5V rail are ok, your 3.3V is probably ok, especially if you aren't having any problems. If you don't have a voltmeter, you can buy an inexpensive one at Sears, or you can buy a decent PSU tester for about $20.

04-24-2008, 04:01 AM	#5 (permalink)
Brogden Fields Registered User Join Date: Apr 2008 Posts: 8 OS: Windows XP SP2	Re: Upgraded from 300W generic to 600W Coolermaster but voltages still low? OK, well I have an analogue AVO, and a DVM, but not the brains to use them obviously! The yellow wire on the Molex is giving a rock steady 12.50V +/- 0.01V, and the red wire 4.81V +/- 0.01V. At the same time, the Mother Board Monitor dashboard is showing the 12V supply as ranging 8.65V - 3.55V, and the 5V ranging 3.82V - 2.52V. And as Jetball pointed out, I am not having any problems. Next step is to uninstall MBM and stop worrying about problems I haven't got. Thanks guys!