Vdroop Vdrop Or something else? 2500K overclock

PolRoger90 said:
With Giga's 10 levels of LLC... I believe level 5 or 6 might be the closest to what I was describing while level 4 will offer a bit more droop under load. You can run with no LLC but it just means your chip will receive more droop under load and thus you'll need to set a higher vcore level in BIOS to compensate for vdroop/vdrop. What you are looking to find out when you overclock is the actual vcore load requirements your chip needs for a given multi...43x, 44x, 45x. under load in Windows via something like CPUZ or HWmonitor.

Your chip may have a somewhat weak imc... so while trying to find out your chips vcore requirements when overclcocked... I would back off on your ram speed and run either 1333Mhz or 1600Mhz dram speed. You should then be able to back off some on the vccio that you are needing to run 43x and higher. You can always come back and overclock your ram later. With SB Intel officially supports 1333 Mhz dram speed so running 1600Mhz and higher dram speeds is actually overclocking the chip's IMC.
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My stock speeds are 1866 and I am pretty sure my board supports 1866 but your saying that by running at 1866 I am, essentially, Overclocking my IMC on the CPU? That does make since due to the fact that I have to run More QPI/VTT than normal. I will try down clocking my ram to 1333 and see if i get a performance drop.

This is the SPD from CPU-Z I was wondering if there would be any advantage to lowering my ram voltage when I downclock the speeds and timings or should I leave it at 1.5v like CPUz says. Stock is 1866 1.5v .
SPDCPUZ.png
 
Sure you may have purchased a kit of 1866 ram and your motherboard has a setting that will allow you to run 1866 but Intel's offficial support or default spec for SB is 1333Mhz. That doesn't mean that you can't run 1600/1866 or 2133+ but when you do... you are actually overclocking the imc of the chip. I'm not saying to just run 1333... I'm saying that while you are exploring the limits of your particular chip that you might want to run 1600 or maybye even 1333 while doing your initial testing. Higher dram speeds means more stress on your cpu's IMC. It is best to work on one component of your o.c at a time instead of multiple aspects all at once. It will make troubleshooting failed o.c.'s easier.

Here is a link to a guide:

http://www.overclockers.com/3-step-guide-overclock-core-i3-i5-i7/
 
There is really no performance difference between DDR3-1600 and 1866, so I would just back down to 1600 while you are troubleshooting. Once you get everything stable, then you can try going back to 1866. Try to limit the variables in the equation. And just leave it a 1.5V, that's a perfectly fine DDR3 voltage for SB.
 
Do you think higher clock speed or lower Vcore voltage could be achieved if I down clock my memory voltage. I am not worried I was just curious to see If it was beneficial for the CPU at all to lower the VDIMM.
 
If the memory is causing the problem, through the IMC, then dropping down the RAM speed could help you get a higher overclock. Maybe, maybe not, but it does take one more thing out of the equation while you are testing.
 
Forceman said:
If the memory is causing the problem, through the IMC, then dropping down the RAM speed could help you get a higher overclock. Maybe, maybe not, but it does take one more thing out of the equation while you are testing.
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I am now stable at

Multi: 33
turbo 45
Vcore: Normal (the bios sets the voltage at 1.355 this is a huge dip below the 1.420 that was required for a stable 45 OC using LLC)
DVID: +0.080
QPI/VTT: 1.070
CPU PLL Overvoltage: Enabled (I had to use this to get the chip to post past 44)
C1E: Enabled
EIST: Enabled
all other c states disabled

I ran Prime 95 for 4 tests with about 40 or so passes which took around 45 minutes to an hour, and IBT on maximum For 5 passes. I am pretty satisfied with sticking at 45 because this was my goal when I bought the system, Even though it seems my chip will not be able to go any further without better cooling.

I am going to play with the voltages and fine tune them a bit I was getting impatient trying to get the system to Post at 45 with just upping one voltages one step at a time because When I would go into the bios to check to make sure the voltages were ok before i booted It would lock up and I had to push the reset button. So I decided to just change the multi to 45 and up the DVID to what I thought would be a safe voltage offset and upped the QPI/VTT as well as enabled CPU PLL Overvoltage.
 
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Good to see you got it working. 1.35 is a decent voltage for 4.5, I wouldn't worry too much about tweaking that down.
 
Thanks for the help forceman you and everyone else have helped tremendously so thanks.

I woke up this morning and had a cold boot issue. In the past once I hit the 45/ 46 multis my system would develop what seems like a cold boot issue where it takes it 2 start ups to post in the mornings or when cold. well this morning I turned the computer on and it had the familiar post issue but it displayed the screen that says "your system has had OC Issues and blah blah blah..." well I upped the DVDID to +.090 and saved the cmos and am running prime95 right now and will run it all day for about 12 hours and see if it fails.

Edit:I decided to try to see if I could get stable at 1866 but I could not when I bumped up to 1866 from 1333 I had so I moved it down to 1600 and have been stable for 1 hour in prime95 Blend I feel that it is better to run 1600 with lower VCCIO rather than trying to get stable at 1866 and haveing to up that voltage even further, am I correct in assuming this? I am going to try to get the VCCIO closer to stock.

I find it odd that when I move my ram to 1600 the timings auto default at 11 11 11 28 1t. I figured that the timings would decrease if I downclocked the ram But I dont know much about how Cas latency and RAM speeds work to be honest so this is more a semi-educated guess.
 
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Just for Good measure Here is the photo of the Prime 95 test I just did for 12 hours. I had to open up IBT In order to get out of EIST mode or C!E. The Max temps are from IBT On standard for 10 passes The Cores read 63 68 68 65 IIRC I know the max was not over 68 on core 1 and 2 but i forget exactly what core 0 and 3 were
prime9512h.png


Multi: x33
Turbo x45
vcore: Normal (Defaults to 1.355)
DVID: +.090
QPI/VTT:1.070
Bios Vcore reading: 1.426
C1E: Enabled
EIST: Enabled
CPU PLL Overvoltage: Enabled
C3 and C6: disabled
Os OC: disabled
RAM Freq.:1600
Ram Timing: 11,11,11,28, 1T
Ram Volt: 1.5
Chipset: Sandy Bridge Rev 09
Bios Version: F1
 
I would now try tightening up your timings at 1600Mhz to 9-10-9-28 1T and also maybe see if you can lower/drop your vccio voltage.
 
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