trouble overclocking a ASUS P8Z68-LX with 2500k

[dansun1222]

Hi folks...happy holidays,

I am a total OCing newbie, but I've read most of the guides that exist out there and still had a couple of questions about the performance I am getting out of my machine.

MBO - ASUS P8Z68-LX
CPU - 2500k
cooling - Hyper 212+
PSU - CORSAIR Enthusiast Series TX750
RAM - CORSAIR 16GB (4 x 4GB) DDR3

The primary source of heartache is that the BIOS for this MBO does not allow a voltage to be manually set. I only have the option for offset mode via BIOS. Additionally, my LLC options are limited to Auto or Disabled.

I currently have a multiplier of 43x and voltage offset of +.005V. Under Prime95 blend test, temps are all below 63C and Core voltage hovers around 1.272 V.

Here are my questions: The core voltage jumps between 1.264 and 1.28 (being read in CPU-Z). Is this bad? I know generally one ups the LLC to correct this, but I don't seem to have expansive LLC options. My guess is that my LLC setting is insufficient to cover the Vdroop.

Additionally, I wasn't sure how to get to 45x safely. Again, my offset of +.005V gives me stability at 43x. However, when I bump up to 45x mulitiplier, I can't get it to boot when I increase the offset up to +.02V. I didn't want to push it much more than that since my understanding of offset would mean this could put me above the 1.4 limit that I see often.

Thanks!

 

[Kenmitch]

Using offset of. 005 gives you 1.28v so to reach 1.40v you'd need offset of around .110 or so to get 1.40v.

Try around .060 or so to see what happens. Check voltage/temps under load....I'm guessing loaded vcore around 1.36v's

You got some playing around room provided your temps are kept inline.

 

[dansun1222]

Of course...I'll give it a shot. Thanks!

What do you think about the vcore bouncing around? Is that a problem?

 

[Kenmitch]

Of course...I'll give it a shot. Thanks!

What do you think about the vcore bouncing around? Is that a problem?

The fluctuations in vcore isn't anything to really worry about and is normal.

Here's an example of my vcore fluctuation. My LLC is set to regular(none) in bios. 12hrs worth of fully loaded temps/voltages as the min/max values were reset once prime was running. If you look at the min and max vcore values it looks like alot till you do the math and realize it's only 64 thousandths of a volt .064

 

[fastamdman]

Also when doing stability testing use LinX or IntelBurnTest with the AVX pack. Just because you can pass prime95 does NOT mean you are stable. I know of many systems that will do p95 all day long but will fail/bsod instantly on LinX. There is a reason LinX and IBT produce more heat on your processors when running, it's because it pushes your processor MUCH harder. Also the AVX pack is needed and or windows 7 service pack one to really push the system. 100+gflops is a lot harder on a system then 50gflops.

 

[BonzaiDuck]

Ok. You've got an ASUS board with the Z68 chipset.

Look in your BIOS screens for a topic called "CPU Power Management" or something like that. There is a setting which I can loosely describe this way: "Extra voltage [to apply/be added to] VCORE in Turbo Mode."

That's your second adjustment feature, besides voltage offset. Even so, I'm puzzled that you can't just take your VCORE setting off "Auto" and set it to a fixed value.

But with these chipsets and the other voltage tweaking features, that should be the last thing you'd want to do.

Running these stress tests, you will find that the voltage fluctuates slightly as the load varies. Your wildest fluctuations would occur when LinX or PRIME95 is "between iterations" with lower CPU usage. What you see in the monitoring software is the result of 1-second sample readings taken from BIOS and a sensor which by itself has a margin of error.

I'm hoping that your motherboard has the same BIOS features as my P8Z68-V-Pro. I don't see why it shouldn't. Are you doing your OC'ing in the "easy" BIOS screen, or the "advanced" BIOS menus? Use the latter.

 

[fastamdman]

You guys, the fluctuations are NOT an error, unless it is at 100% load. For example if you are running LinX and you have 1.4 vcore in bios and you have 1.38 at full load you are losing .02 to the voltage loss from your motherboard/power supply.

Now if you generally have 1.38 but see a dip to 1.35 this is NOT a bad thing. This is simply the voltages DECREASING because the load decreases. When LinX is running you have 100gflops running through your processor, when it stops to "post" the information in the window it's no longer pushing the processor hard so the voltages drop. This will only be seen with eist/c1/ce etc etc. Just like at idle how are speeds drop to 1600mhz and .096 volts roughly, our cpus will drop voltage slightly in linx and other apps when it's not needed.

For example my max load vcore for LinX is NOT the same as my max load vcore for folding at home and i would assume its not the max for p95. Just because the cpu is at 100% doesn't mean it is truly being stressed 100%.

Another good example of this is LinX/IBT with the AVX pack aka windows 7 with service pack 1 and the correct library. With this setup your cpu is being pushes 100% to it's knees, without it, it's pushed half as hard if that makes any sense but it's still about twice as hard as p95. These are rough estimates but I assure you there have been people that pass without avx and fail with avx. The difference between 50-60 gflops and 100-120+ is MASSIVE and A LOT more stress on the operating system, memory, the memory controller, the cpu itself etc. You might also see an increase in voltages needed to be stable etc etc.

Either way, don't worry about the max/minimum voltages you see with your monitoring programs because your vcore is going to lower if you have the speed step settings etc on.

Moral of the story, leave eist on, run the lowest vcore you need for stability and you win. Anything between 1.4 and 1.425 is safe for 24/7 in my opinion. I have done EXTENSIVE testing with SB chips, hell I have put 1.6 volts through my chips on multiple occasions, but no matter what people tell you, these chips have not been out long enough to know the maximum safe voltages. I know plenty of people running 1.5ghz on water for 24/7 overclocks at 5.2ghz, but then again these are die hard oc'ers =P

/Rant over, enjoy the facts and tips =D

 

[dansun1222]

Thanks for the responses guys.
BonzaiDuck - There are significantly less options for OCing with the -LX version of the board as opposed to the PRO. You can't set a manual VCORE, only offset. This is in the advanced BIO screen. Additionally, there are no Digi+VRM options.

fastamdman - Thanks for the suggestions. I have been using both Prime95 and LinX and haven't had any BSOD's or resets. Is there a reason to use IBT in addition to LinX?