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Need help with weird overclocking problem (E8400 to 3.6ghz).

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June 11, 2008 3:43:21 PM

Hi,

First time ever overclocking, hopefully this question doesn't end up being too "noob". I have read a gajillion guides on this as well but not sure what to make of my particular situation.

I have a E8400 (3ghz), Asus P5K-E (P35) motherboard, Corsair DDR2-800mgz ram (5-5-5-18,1.9v), and 8800 GTS 512mb videocard. I have also installed an aftermarket cooler (Arctic Freezer 7 Pro). As well I have 6 120mm fans (3 outflow from back/top and 3 inflow from front/side/bottom).

At 3.0ghz with all the bios settings at auto, the computer starts with a vcore of 1.1125v. Idle temps are CPU = 27 Core 1 = 40 Core 2 = 36. Load temps (Prime 95) are CPU = 36 Core 1 = 49 Core 2 = 43.

So far so good, everything is normal, and no errors in Prime 95 as should be expected. Now onto how I set the bios for the overclock to 3.6ghz.

At first, all I did was change the the FSB to 400, PCI-E to 100, Ram manually to 5-5-5-18, 1.9v @ DDR2-800mhz. Everything else was set to auto including vcore. The system started fine, ran windows, and CPU-Z showed vcore at 1.19v. I'm pretty sure I ran Prime95 at this setting and the computer rebooted 20 seconds in.

After doing more reading, I found that the stock voltage isn't actually 1.1125v (which my system starts at "normally") but 1.2250v. This confused me to no end because I thought 1.1125v was the stock voltage as that was what the computer started up at originally (and is completely fine running with stress tests, etc). Anyways, so I then figured I would need to set the vcore manually.

Going back into the bios, leaving everything else the same, I manually put the vcore to 1.2250v. The computer, after restarting however, would crash at or around the bios screen, leaving a blank screen, or still image of part of the bios image. Never got to Windows. I had to turn the computer off fully, start it, and it told me that OC had failed, and it let me go back into the bios. This confuses me to no end because apparently 1.2250v is the stock voltage, and the computer should run fine.

Anyhelp would be greatly appreciated. Thank you!
a b K Overclocking
June 11, 2008 5:05:05 PM

I'd back down a bit on your FSB to make sure you're stable first, then slowly work your way back up to 400FSB. Yes, 1.225 is the VID, but you are also at a 600Mhz OC.

It's true that 600mhz is easy OC for an E8400, but each board is different, even among same model boards.

Start back at 3200Ghz and follow the OC guides, using incremental FSB mhz increases. Yes, this is slow and time consumming, but it also ensures you are more stable at each increase.

***EDIT*** One more thing, when you increase your FSB, you also have to change your memory ratio. Make sure you use a ratio that will keep memory around the 800Mhz
June 11, 2008 6:07:26 PM

I will definitely try the incremental model. However, I'm still confused as to why it will load Windows when I set Vcore to "Auto" (CPUZ registers it at 1.19v), yet when I manually set it to 1.225v, it won't even get past the BIOS.
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June 11, 2008 6:31:56 PM

Check the memory ratio. That is what got me when I started OCing. At 400MHz FSB, you wat to change the memory ratio so it shows up as 800MHz memory.
a b K Overclocking
June 11, 2008 6:36:52 PM

demare27 said:
I will definitely try the incremental model. However, I'm still confused as to why it will load Windows when I set Vcore to "Auto" (CPUZ registers it at 1.19v), yet when I manually set it to 1.225v, it won't even get past the BIOS.


Auto. For my board, Asus P5N-D actually overvoltages my processor. In CPUz, auto will register as 1.24v or around there. While at the same CPU speed, I can keep it stable with a manual BIOS voltage setting at 1.235v, CPUz will show 1.20v.
June 11, 2008 9:10:37 PM

Figured it out. When I put in 1.325v as the manual vcore in the bios for example. The ACTUAL vcore (as reported by CPU-Z or the Hardware monitor within the bios) is 1.216v. Now this strikes me as completely bizarre but it works at 3.6ghz under load so... WEIRD!
!