Can't overclock core2duo 6600 even 100mhz!!

[kypron7]

Hi, I have never really bothered with overclocking before, but this morning I got the urge to bump up my core 2 duo 6600 from 2.4 to maybe about 2.7 ghz. Within the first 100 mhz overclock, though, orthos failed immediately! So I clocked it back down.

I am running the newest 0803 bios with the asus p5b vanilla with a core2 duo 6600 revision b2 stepping 6. The first thing I did was lower the timings of my ddr2-667 ram to ddr2-533 5-5-5-15. I then moved the FSB from 266 to 276. (I left the cpu voltage on auto)
Well, it booted into windows fine, but like I said, Orthos gave immediate errors.

Anyone have some ideas as to why this occured? I have been running Orthos for a half hour no errors now at 2.4 ghz. Hmmmmmm.

 

[hnzw rui]

Set cpu voltage to manual. For minimal overclock, it shouldn't need more voltage. Have you tried memtest?

 

[kypron7]

Hi, yes I have tested out memtest 86+ 2.1, and everything checks out ok for 10+ hours. I just tried to OC again but I manually set the cpu voltage to 1.25, and raising the bus from 266 to 276 causes immediate errors.

 

[GuitarDaddy]

I'm also guessing that it has something to do with ram. Can you post a screen shot of CPUz with the memory tab open?

 

[kypron7]

Hmm, I'm not sure how to put a screenshot up. But it says

under SPD tab

all four sticks show as 1024mb ddr2-667
at 533 4-4-4-12 1.8v, at 667 5-5-5-15 1.8v

under Memory Tab

ddr2 - 4096 mb in dual channel symmetric
266.9 1:1 ratio 5-5-5-15 2T

other info is greyed out



My ram is set well within spec, it should be able to do up to 667 at 5-5-5-15, and I only started it at 533 5-5-5-15 when overclocking.


I read the sticky at the top of this forum about overclocking, I didn't do anything different than what it says, though I did leave speedstep and that other power management thing on in the bios...

 

[kypron7]

Ok, I've figured out that it is indeed the ram that is the culprit. If I change it to 667 5-5-5-15 with no overclocking, the system hangs at the splash screen. I had to remove two sticks to get it into the bios, and lower it to 533.

Looks like I'm out of luck for oc'ing this time around.

 

[GuitarDaddy]

What is your vdimm set at 1.8v? What's the specified vdimm for those sticks?

You may just need to increase the vdimm (ram voltage), try bumping to 2.0v and see if it will pass at DDR667

 

[kypron7]

These sticks are all rated at 1.8v. Is it harmful to go above this? I know a lot of high end memory is rated for 2.0 v and above, but these sticks are cheap samsung. I should note, as well, that 2 sticks are slightly different than the other two sticks. All are 667 and samsung, but 2 of them I bought at a later time, and have a couple slightly different subtimings shown in CPU-Z.

 

[lou61166]

Remove 2 gigs of ram and try that.i also went through memory problems when i tried overclocking the first time.

 

[TC91]

you likely have to increase the voltage on the ram and/or northbridge, mch to get 4 sticks stable. i had to bump my ram voltage by 0.1 to get the 4 sticks to run stably @ stock. ram voltages 1.8-2.1 IMO are very safe voltages for ddr2 ram.