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Undervolting Power Supply?

M

MarkFahey

n00b
Joined
Jan 10, 2005
Messages
15
Hi Everyone,

Here is a question for you tech experts. Can a power supply that is undervolting cause any damage to PC components? If so, what would likely be damaged? CPU, Video Card, Memory, etc? If damage can result then is it possible that a component would still fuction but exibit strange anomiles like graphic or data corruption? Also would it matter how long the system was running with this situation, for example several months or would damage occur within a small amount of time?

The reason I am asking this question is because I just recently found out that my Antec True Power 550 has been running with the +12 and +5 volt rails low. The 12v rail was dipping to 11.855 and the 5v rail was dipping to 4.811.

Thanks!

Mark
 
11.855 on the 12 and 4.811 on the 5 aren't low, they are well within specs. Specs are +/- 5% so a 12V rail can go all the way down to 11.4 and a 5V rail can go to 4.75.
 
A slight amount like that won't hurt, but when the voltage goes really low, disk drive motors can draw a lot more current, and any voltage regulators, like the one on the mobo for the CPU core voltage, can strain by letting the current flow too long during each cycle.
 
Yea I was just about to ask the same question.

I got a new opty 146 today and the previous owner got it up to 2.9 but I can't even hit 2.65 to boot into windows.

My 12v rail is at 11.91 and 5v @ 5.02 and 3v@3.12

Do you think the powersupply is limiting it? It does have dual 12v rails 36A all together.

Its an Xcilio 450W I think.
 
clickclickw00t said:
Yea I was just about to ask the same question.

I got a new opty 146 today and the previous owner got it up to 2.9 but I can't even hit 2.65 to boot into windows.

My 12v rail is at 11.91 and 5v @ 5.02 and 3v@3.12

Do you think the powersupply is limiting it? It does have dual 12v rails 36A all together.

Its an Xcilio 450W I think.
Click to expand...

The number of things that limit an OC are much more varied than just a PSU. Those are inspec readings....are they from software (BIOS is software)?
 
Those readings are from the Bios.

Also, I have a DFI NF3 Ultra-D AGP.

The rest of the stuff is in my sig.

I have my CPU running at 2.5ghz and memory at 280 2.5-3-3-7
I have an XP-90 and a Tornado. I'm giving the CPU 1.6v becuase the board unvolts. Memory I'm giving 2.8v
 
You need to get a digital multimeter on a molex connector and see what the system is doing at idle, booting, and loads. On my system, the 12V rail is about 12.3V on a multimeter, but software monitoring reports 12.0-12.1 V. Don't trust anything until you get a multimeter on it. And even so 11.7-11.8V is acceptable.
 
I dunno. You can get one at the auto parts store for cheap probably. Or maybe Walmart even.
 
Harbor Freight sometimes has digital multimeters for as little as $3, and one person managed to buy one from Sears for $5-6. Stay away from meters that use button batteries because they won't last long, and a set can cost as much as the meter. All digital meters seem to be very accurate, but try to avoid those rated for just 2.5 digits (200 count) because with them the reading can be really inaccurate if the first digit in the reading is "2", i.e., 2.10000V will be displayed as 2.1V, but because the rightmost digit can't be trusted to better than -+ 1 count, this could be 2.0V or 2.2V, an error of about 5%. You want 3.5 digits or at least 2000 count.
 
A multimeter is useful but you also want to use a utility like Speedfan. The voltage charts can show you how much ripple and noise is on your rails. A multimeter shows my 12V as 11.7, however Speedfan shows it cycling rapidly between 11.5 to 11.8 (which isn't good... there shouldn't be 0.3 volts of crap riding on the 12V rail).
 
How would I go about connecting the one from the audio parts store to acomputer?

Does it havea molex connector or what?
 
No, the mutimeter comes with a positive and a negatice lead. Connect the negative (black) lead on the multimeter to a black wire on a spare molex connector. The center two wire are black, and either one is fine.

Connect the red (positive) lead on the multimeter to the yellow lead on the molex connector. This will give you the reading from the 12V rail. If you connect the red on the multimeter to the read on the molex connector, it will give you the reading from the 5V rail.

To get the 3.3V rail, you have to use more than one connector, but I forget off the top of my head. Search on google, I think you will find pictures of what I am talking about too.
 
Does this require taking apart a molex connector?

Can someone find me a Multimeter made for power supplys that I just have to plug into a molex connector? That would be great becuaseI have no clue where to look. Thanks
 
It's really simple, you sound like you want to make this more complicated than it is. You do not have to take anything apart. Just touch a few leads together and read the screen on the multimeter. Go to a partts store, Sears, Walmart, etc. and pick up a cheap multimeter...
 
Frank4d said:
A multimeter is useful but you also want to use a utility like Speedfan. The voltage charts can show you how much ripple and noise is on your rails. A multimeter shows my 12V as 11.7, however Speedfan shows it cycling rapidly between 11.5 to 11.8 (which isn't good... there shouldn't be 0.3 volts of crap riding on the 12V rail).
Click to expand...

Speedfan only reads what the motherboard sensor says like any other software utility.....any change in voltage of .3 volts would be read by a multimeter. For ripple you need an o-scope.

Speedfan=useless
 
BIOS and Speedfan and all other software monitoring pulls the data from the same source
the system management bus

SMBus

and the output is only as good as the sensor input the mobo manufacturer employs
 
Spectre said:
Speedfan only reads what the motherboard sensor says like any other software utility.....any change in voltage of .3 volts would be read by a multimeter. For ripple you need an o-scope.

Speedfan=useless
Click to expand...

A multimeter won't show .3 volt ripple at high frequency, nor will it show voltage spikes or dips. It shows the average voltage over time. And last time I checked o-scopes are too expensive for most home PC users.

Speedfan=useful when you don't have an o-scope
 
Thanks for the great feedback guys!

The reason I am asking this question is that I have been experencing some strange graphics anomiles. The problem I am having is jittery, jerky, ghosting graphics not only happening on my desktop but in games as well. When I scroll through text or images in IE, Firefox, Word, etc... the movement is not smooth and is stuttering/ghosting. As well as when dragging a window across my desktop. It gets worse the faster I increase the movement or scroll. If I move the mouse super slow it is nice and smooth with no jitter but as soon as I start to speed up the movement is starts. It not only happens with the mouse but also with the keyboard arrow keys as well. So it is not mouse related.

It's similar to a Vsync tearing, but the text, image, or window has a blurring effect that is jittering or ghosting while its moving and leaves a bit of itself behind that has to catch up with itself. Where with only a Vsync tear you get the stepping tearing but not the blurring that I am getting. When I'm in a game like BF2 or Americas Army, when I turn with the mouse or strafe with the keyboard objects like trees, edges of buildings, other players, etc are ghosting and jittery where again it takes a second for the image to catch up with itself, like a graphics lag.

I just installed an nVidia eVga 6800 AGP into my ASUS P4C800-E. I am running a P4 2.4b, 2 x Corsair 512M PC3200XL's running in duel channel mode, Audigy 2, 2 x WD 120G 2mb HD's, Antec True Power-II 550W PSU, Dell 2001FP Monitor. Before this nVidia card, I was running an ATI 9700 Pro and was experiencing the same problem with that card. I did a fresh Windows XP SP2 install with this new video card, latest Intel chipset drivers, nVidia drivers and all the latest XP updates. I have also tried several older Forceware drivers.

I also tried running another OS using the Knoppix Linux 4.01 Bootable DVD version and the jitter/ghosting was even happening under Linux. So that definatly rules out any problems with Windows XP. I even moved my rig to a friends house to rule out any EMI interference I might have had at mine.

What's really weird about this issue is that my system used to run great, no graphics jitters and smooth like silk. Even when I had my ATI 9700 Pro in it. Then all of a sudden one day several weeks ago it started having this problem. I thought that it may be graphics card related, and anyway it was about time to upgrade my card so I thought that would fix it.

I have tried my rig on two other different monitors - one was a iiyama 21" CRT and the other was another Dell 2001FP. I have swapped out the Mobo for another Brand New ASUS P4C800-E, I have tried different memory, different sound card, replaced the hard drives, replaced the IDE cables, disconnected all fans and optical drives as well as replacing the PSU with a brand new Antec TP-II 550 that is running very tight on all rails.

The only other thing I haven't replaced in the CPU. Is it possible that the old PSU might have damaged the CPU? Or could an Intel processor all of a sudden start causing issues like this? Have you guys ever heard of an Intel CPU causing this kind of graphical problem?

To this point I guess I have eliminated just about everything I could think of that would cause this problem. This should not be happening, my 2D scrolling and dragging and my 3D movement in games should be smooth without jitters/ghosting. This problem really has me stumped.
 
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