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Fan voltage. How much is too much?

post #1 of 11
Thread Starter 
Hi All, I'm running a 3.2 Prescott O/Ced to 4.0ghz w/ a TT Big Typhoon. Everthing is rock solid at 1.55v, but I still think thats a bit too high on the voltage. I'm wondering if my case fans are sucking too much power from the rest of the board.

I've got 4 case fans, 2 at the back connected to the PSU and 2 at the front connected to the board. The 2 at the front are pretty powerful and run at about 3400 rpms each. The 2 fans (Antec) at the back came with the case and have molex connectors and are rated at about 2400 rpm.

I've been doing a bit of testing and when I unplug those 2 fans at the front I'm stable at 1.50v. I haven't tested it w/o the fanw for more than a few hours, but with those fans on and @ 1.50v i get errors in p95 within minutes.

The rated voltage on these 2 front fans are 12v so connecting them to the molex is a waste of time as they are only barely spinning.

I"m going to test without those 2 fans overnight and see how i go.

Now for the worrying part, even though my system is stable ever so often I hear a sound coming from the case that sounds like.........uuhh dunno something is straining or worse shorting sort of like an HDD that reads for a sec then stops. It's too random for me to get close enough to listen to really ID where its coming from though.

Do you guys think those fans are too powerful for my board ? and any reccommendations on some better ones that i can plug straight to my psu ??

Thanks
post #2 of 11
1.55 is no where near too high, I ran mine at 1.7 for a few weeks back when I was determined to get it to work at 4GHz, trust me the Big Typhoon is more than up to cooling it and an OCZ PSU is more than up to powering it, my brother also has a Big Typhoon and I fed his 4400+ X2 all the way up to 1.89v with no problems!

EDIT/// read rest of post, I have the same problem with the noise but have not noticed any instability and never thought about it....next time I hear it i'll try unplugging my case fans and see how that goes.
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post #3 of 11
I'd get adaptors and remove them from the mb. Only fan running off it should be the cpu fan.
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post #4 of 11
Thread Starter 
Quote:
Originally Posted by Remonster
1.55 is no where near too high, I ran mine at 1.7 for a few weeks back when I was determined to get it to work at 4GHz, trust me the Big Typhoon is more than up to cooling it and an OCZ PSU is more than up to powering it, my brother also has a Big Typhoon and I fed his 4400+ X2 all the way up to 1.89v with no problems!

EDIT/// read rest of post, I have the same problem with the noise but have not noticed any instability and never thought about it....next time I hear it i'll try unplugging my case fans and see how that goes.
I'm not too bothered about running it at 1.55v but I've read that anything over 1.6. won't last very long. And I still hope to take it up to 4.2 and run it 24/7.

I've heard of a few people running them @ 4ghz with 1.46 volts and stable. If I can get more speed with less voltage then when I up the FSB i can use that voltage and still keep it safe.

I'm testing now to see how it runs w/o those 2 fans.
post #5 of 11
Thread Starter 
Quote:
Originally Posted by busa
I'd get adaptors and remove them from the mb. Only fan running off it should be the cpu fan.
Did that today actually, didn't help at all since the voltage from the molex didn't seem like it could power the fans. They were barely moving any air at all. The fans are rated at 12v so I guess thats why.

Case temps went up by about 5 degrees too.

I'm looking in to getting some decent fans w/ molex connectors.
post #6 of 11
Quote:
Originally Posted by gunner14
Did that today actually, didn't help at all since the voltage from the molex didn't seem like it could power the fans. They were barely moving any air at all. The fans are rated at 12v so I guess thats why.

Case temps went up by about 5 degrees too.

I'm looking in to getting some decent fans w/ molex connectors.
Why would the mobo voltage be higher than the molex voltage? That seems odd.
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post #7 of 11
Thread Starter 
Quote:
Originally Posted by CyberDruid
Why would the mobo voltage be higher than the molex voltage? That seems odd.

I realised the adapter I had was pulling power from the 5v rail instead of the 12v. I got that fixed by cutting and moving the wire over to the 12v. So atleast now I got my fans at 100%. Guess I'll see if it was the fans that were pulling voltage from the cpu.
post #8 of 11
I've never run a Prescott over 1.5V and usually 1.45V or less as I have found that the Prescott does not respond all that well to voltage changes. Just because the processor is being cooled it does not take into account the electrostatic migration and thus the need for ECC data validation being implimented to correct the data errors from the migration.

Within CPUs, this electrostatic charge is a dangerous entity if it begins to affect the other transistors around it. That is why it is so difficult for computer companies to develop new chips - they must take into account the need for buffering room between the transistors within the chip. As a particular transistor's electrostatic field increases, it can cause damage to the other transistors around it. Electrostatic migration shouldn't be a problem for most overclocked processors unless you exceed the company's maximum core frequency for that particular model of core. If you do so, you will indeed shorten the life expectancy of the processor regardless of the "coolness" of the processor.

[Blatant Personal Opinion]
Overclocking is an art to find the maximal abilities of the system while not damaging the parts more than simple use would commit.
[End Blatant Personal Opinion]

R
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post #9 of 11
Thread Starter 
Quote:
Originally Posted by Ropey
I've never run a Prescott over 1.5V and usually 1.45V or less as I have found that the Prescott does not respond all that well to voltage changes. Just because the processor is being cooled it does not take into account the electrostatic migration and thus the need for ECC data validation being implimented to correct the data errors from the migration.

[Blatant Personal Opinion]
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[End Blatant Personal Opinion]

R
Thanks for your knowlege transfer Ropey

I really dont wanna kill the cpu, I've been shooting for 4ghz hence the 1.55v but --> Since I upgraded to a 520w psu from a 400w I actually get 4ghz stable now with 1.525v. Before that I got up to around 3800mhz with about 1.45 v.

The cpu is being well fed powerwise so I dunno why I can't get better speeds a lower voltage.
post #10 of 11
The socket 478 is not a very stable platform for speeds in excess of 3.8GHz. There are those who make it there but not nearly as many as those who do not. This is one major reason for the move to LGA 775 sockets as the new format is more stable at higher speeds with the power requirements of the Prescott. Northwood "C" had a hard time going past 3.8GHz but the processors power requirements were minimal in comparison to Prescott's hunger. Prescott could but was (and is) restricted by the socket 478 structure so you will find most (not all but certainly most) 4.0+GHz (stable) running on the 775 platform.

This has been my experience at any rate.

Edit: As well, those who make it there on Prescott usually end up with a system shelf life that is rather short in comparison to those who make it there on Northwood. The 478 boards tend to burn out with Prescott and this I have seen firsthand.

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