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Overclocking voltage worries

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  • Overclocking
Last response: in Overclocking
November 23, 2007 2:21:17 PM

First of all, my system specs are:
Antec True Power II 550W
Intel Bad Axe Rev 306 using the latest stock BIOS
OCZ Special Ops Edition DDR2 667 memory (rated at 4-4-4-12 and 1.9v but lifetime warranty up to 2.2v)
Core 2 Duo E6600 (2.4 GHz stock)
Zalman 9500 Copper fan with Arctic Silver 5
eVGA GeForce 7950GT
Zalman VGA Copper fan
http://thechuckster.homelinux.com/~chuck/build1.jpg

To overclock my CPU to 3.1 GHz, I went into the Advanced Chipset menu of the BIOS and set the host burn-in to positive 30%. I left PCI and PCI Express burn-ins to default. Then I bumped up the MCH voltage to 1.525v and the FSB voltage to 1.271v. For 1:1 ratio, I set the memory to 553 MHz 5-5-5-15 at 2.2v. My BIOS does not have a strap setting (is that what the burn-in does?), no power slope (supposedly this automatically ramps up the CPU voltage when under load), or CPU voltage (is that what the FSB voltage override does?) settings. Of course, I disabled the Intel Speed Step feature, and I set all the fans to the max. It was Prime95 stable for a 3 hour test, and my CPU is now running at 3.1 GHz. :D 

Then, I brought down the memory to 4-4-4-12 @ 2.2v and Prime95 tested overnight. Stable, and the 3D Mark results are wonderfully tempting. ;) 
http://thechuckster.homelinux.com/~chuck/overclock.png
http://thechuckster.homelinux.com/~chuck/3dmark_results...

Temperatures seem a little uncomfortably high (word around the street is the board sensors are 10C too high... can someone verify?). The idle was 40C and load at 50C at stock frequencies... now its 43C idle and 58C load.

So I took down the MCH voltage to stock, and ran Prime95 for three hours... still stable.
Then, I brought the memory back down to 1.9v. I'm running Prime95 right now... it's been almost an hour, and things seem stable. Now I just have the FSB voltage at 1.271v.

My question is... are these voltages reasonable for the 3.1 GHz overclock? I'm completely new to overclocking, so I have no idea beyond here. I can just keep listing all of my questions: Should I bring all of the lowered voltages back up as a safety net? Was I overvolting the system to begin with? Should I bring down the FSB voltage and run it at stock as well? Am I undervolting the system for my 3.1 GHz clock speed? Is one instance of Prime95 an adequate stability test? How long should I run it? What I don't want to do is kill my system (or any components)... is this overclocking a bad idea then? Should I go back to stock speeds? How much of a lifetime should I expect of my PC? Am I doing something extremely stupid that I haven't picked up on? How unstable is my PC going to be? Will I fry anything?

I would greatly appreciate it if an experienced OCer could fill me in on all of the details. I don't plan on maxing my system out... I just want a stable speed boost for day-to-day computing that won't introduce risk of frying things. How much risk is there at this point? What can I do to correct that risk?

More about : overclocking voltage worries

November 23, 2007 3:40:45 PM

Your temps seem high. Are you using the stock HS? or are you using something else. Your case pic shows the stock HS. Also, your case very cluttered. You could be experiencing hot zones and improper air flow.

Based on my experience, good air flow can lower temps by at least 5c and I believe it can lower much more under certain circumstances.

As for voltages. To obtain mine (stable 11hrs dual prime 95) I have to over volt my memory to +.01 (2.3v), mch by +.1 and I am lucky enough that I can lower my vcore to 1.125 which helps explain my temps. During my 11hr test my highest temp was 44c per speedfan. I idle at 31-33c.

Before you worry about voltages, I would re route your wires and improve airflow. As an example, I have 2x140mm out take fans, 2x140mm intake fans, 1x120mm intake and 1x120mm out. Lots of air moving. I have as many of the wires hidden our routed so that they are out of the way to help airflow.
November 23, 2007 3:59:15 PM



Here is a pic of my case. fan at bottom is 140mm. Fan on door (not pictured) is 140mm. fan by heatsink at back of case is 120mm. 2 x140mm out take fans at top of case by the heatsink. 120mm fan in front of case as intake and I also have an 80mm fan blowing on the back of the MB

As you can hopefully see, all the wires are out of the way so that they dont hinder air movement. It could be that your HS fan is recirculating hot air instead of getting fresh air.


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November 23, 2007 4:03:51 PM

Now I'm using the Zalman fan instead (you can see it in the picture). I took the picture right before I installed it. I'll see what I can do about the cables. What did you use to secure them to the case?
November 23, 2007 4:27:40 PM

I routed most of mine to the back of the mobo tray and taped them down using electrical tape. The ones in front are tied to the mobo tray either with the system that came with my case or some cable ties. You want it to be as close to the mobo tray as possible.

What do you have for fans? just 2?
November 23, 2007 6:34:32 PM

I have two 80 mm intake fans in the front, an 80 mm exhaust on top, and an 80 mm exhaust in the back. They are all very noisy -- even though they aren't cooling very much, they sound like a leaf blower. The power supply has a 120 mm fan on the bottom that brings air out of the case through the grid on the back of the PSU.

Here's a picture from the front showing the two 80 mm intake fans:
http://thechuckster.homelinux.com/~chuck/build2.jpg
November 23, 2007 6:40:33 PM

yep, lots of wires in the way to stop the from flowing to your HS. I dont know much about your HS, but I would imagine its better than the stock HS
November 23, 2007 8:01:40 PM

Do you really think the wires have that much of an effect? I'm more worried about fan size (most cases are 120 mm) and that my case is too big.
November 23, 2007 9:19:00 PM

Well, you can upgrade your fans, but yes, the big bunch of wire prevents air from moving.

It really shouldnt take you more than 20mins to fix it..
November 23, 2007 10:04:23 PM

I discovered something! My rear case fan is actually an intake fan designed to route air up to the top exhaust case fan. So I have my Zalman fan pointing backwards... that's gotta be affecting temperatures!
November 24, 2007 1:13:35 AM

See... you want the front ones blowing in and the back one blowing out.

To show what a difference good air flow can make, I installed a 140mm fan in the front just a little while ago. This is in addition to my other fans



I have been running dual prime95's for about 45mins now and my max temp per speedfan is 40c. I now idle at 29-31c. A drop of at least 4c on the full load. smaller drop on the idle..