************** UPDATE *****************
After messing around with this forever I finally found the culprit, a loose connector inside the molex connecting the PSU to motherboard. A little tweaking with a needle and it's steady at 3.26V
 
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Up until 2 months ago I had been using a Koolance PSU and the 3.3V rail always ran low, in the 3.14V to 3.2V range. I wasn't thrilled about it but the system was stable so whatever. Then I switched to a Corsair PSU and one of the first things I checked was the 3.3V rail and it was dead on at 3.3V. Two days ago, my Areca RAID card starts sending me warning emails that the 3.3V rail is low and sure enough, it's now way down at 3.02V !!
 
In all cases, the BIOS, E-LEET, the Areca RAID card, and a DMM all report voltages within a couple hundred millivolts.
 
All the voltages look like this:
 
Power +12V >> 12.038 V
Power +5V >> 5.053 V
Power +3.3V >> 3.024 V
SATA PHY +2.5V >> 2.544 V
DDR-II +1.8V >> 1.872 V
PCI-E +1.8V >> 1.872 V
CPU +1.8V >> 1.872 V
CPU +1.2V >> 1.232 V
DDR-II +0.9V >> 0.928 V  
It seems unlikely that two PSU's in a row would have the same problem so anybody know what else could be causing this?
 
William.

Sorry, I thought everyone knew a DMM was a Digital Multi Meter
 
William.

I measured it at the molex connector on the PSU. All my HD's are on the Areca so without it I can only boot into the bios screen. I could measure it again at that point but it seems to me that a lot of other stuff wouldn't be fully powered up at that point?
 
William.

I'm all about the process of elimination, but not really sure what all uses the 3.3V rail.
 
Unless the Areca is the most likely culprit it's going to have to be the last step though as to really test without it means loading windows onto another drive.  And do SSD's or other HD's use 3.3V's? Unplugging the Areca also means 12 drives will just be idling.
 
William.

wsmeyer

Well, I pulled all the RAM out and booted with just one stick in slot one and it was back at 3.26V

Next I test each stick by itself in slot one and all resulted in 3.26V

Then I put all the sticks back in booted and was at 3.21V

I'd be happy with that but now after 4 hours of use it has slipped down to 3.14V

William.

3.14 is as low as you ever want to see it. as thats just barley in spec.