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SandyBridge I5-2500K OverClocked 4.5GHz Questions Help!

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July 8, 2011 8:29:53 PM

SandyBridge I5-2500K OverClocked 4.5GHz Questions Help!
Hi, this is my first time overclocking and I did a whole lot of research before trying it. There is a lot of information out there about overclocking and many areas are somewhat confusing for me so I hope experts here could give me there advice on my overclocking; Thank you in advance for your help!

CPU: Intel core I5 2500K Sandy Bridge (OCing now!)
HSF: Cooler Master Hyper 212 Plus (Artic silver 5)
MOBO: ASRock P67 EXTREME4 (B3) LGA 1155 Intel
GPU: EVGA GeForce SC GTX 460 (will SLI later)
RAM: CORSAIR Vengeance 8GB DDR3 1600 (Maybe OC later)
SSD: Kingston SSDNow V+100 SVP100S2/96G (Tweaked)
HDD: Seagate Barracuda ST31000524AS 1TB 7200RPM SATA 6GB
OD: LITE-ON CD/DVD Burner - iHAS124-04
PSU: Corsair Enthusiast Series TX750 v2 750-Watt 80 Plus Bronze Certified
CASE: LIAN LI Lancool PC-K63 Black Steel ATX Mid Tower
OS: Window 7 Professional

1st Question: First I would like to ask, what is a stable Vcore 24/7 Overclocked PC with I5-2500K SandyBridge CPU? I tried looking for the answer, but most of what I found was too old (in Jan.) and a large mix of 3.5v – 5.2v 24/7 stability.

2nd Question: I read somewhere that when OCing my CPU the turbo boost function will automatically shut down or disable itself, is that true?

3rd Question: I am trying to OC my CPU to 4.5GHz and have my Turbo boost set on default and short Duration Power limit: 210 and Long duration power limit: 200 with auto voltage. My question is do I need to manually set these settings or leave it at automatic? If I have to set it are those numbers ok? I use an educated guess for those numbers by comparing them with others; I really do not know much about these settings. (I know question 3 is really multiple part questions :) )

4th Question: Is the offset adding or subtracting from the VID? And if not what is it offsetting?

5th Question: Does Internal PLL Overvoltage need to be enabled for OCing? I researched it online and found mix answers with some having them on and some having them off. I read that having it on is helpful with voltage stability when OCing extremely high (4.7 and above). So I am OCing to 4.5 right now with PLL overvoltage disable and it seems fine, but with it on does it make it better?

I am able to run Prime95 for 1hr 15 minutes without issues with the following settings (please let me know what you think about my setting and how I may improve it):

UEFI version P67 Extreme P1.60
Load Optimized CPU OC settings: Default
CPU Max Ratio: 45
Internal PLL Overvoltage: Disable
Turbo Boost Power Limit: Manual
SDPL: 220
LDPL: 200
Additional Turbo Voltage: Auto
Core Current Limit: 200
Spread Spectrum: Disabled
Power Saving Mode: Disabled
CPU Core Voltage: fluctuate between 1.248v – 1.256v
Offset Voltage: -0.055v
LLC: Level 3 (there are 5 levels [1-5])
Prime95 Load: vcore fluctuate between 1.264v and 1.272v
IDLE: fluctuate between 0.928v – 1.064v

6th Question: is this consider stable, I mean is it normal for the vcore to fluctuate?

Change LLC to Level 1 Prime95 Test
Next I reboot to UEFI and change my LLC level to “1” (I read somewhere that the lower the LLC the better). The change in LLC crashed within 15 minutes of running Prime95. Vcore on load fluctuate between 1.312v, 1.320, and 1.328 before BSOD.

7th Question: With LLC is it better to have a lower (level 1) than having it at higher (level 5)?
Change back to previous stable Overclocked settle with LLC lev. 3

8th Question: Now I change back the LLC to level 3 and ran Prime95 again and the core voltage has change since last time. Now it is running at 1.272v and 1.280, is that normal for it to have different core voltage under load with the same settings?

Below are my current stable Overclocked 4.5GHz CPU UEFI screen shots, CPU-Z, Speedfan, etcetera:













Any Advice in addition to my question are welcome and appreciated, Thank you!
July 9, 2011 12:22:40 AM

Just finish running Prime95 torture test for 5hrs with stable temperatures in the 50s and lower 60’s. 10-15 minutes after ending Prime95 while surfing the web I get BSOD. So no problem under load with vcore at 1.272v and 1.280v running Prime95, but afterwards it BSOD while IDLE (or near IDLE speed). Now I plan to increase my offset to -.050 from -.055 to see if it stabilizes while idle. Does anyone agree with this? Please let me know what you might do next to stabilize this OC. Thank you.
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a b à CPUs
a b K Overclocking
July 9, 2011 1:43:25 AM

1st Answer:
To keep Sandy Bridge happy for long-term overclock:
1. Keep peak Prime95 core temps below 75ºC
2. Keep CPU voltage below 1.4v

2nd Answer:
ASRock boards overclock using the Turbo Boost function. The speed you set is the final clock speed -- it will not Turbo Boost higher than that.

3rd Answer:
Manually setting them is better than Auto. 220 and 200 should be fine. Change Long Duration Maintained to 56.

4th Answer:
Offset mode starts at 1.2v (the CPU default) and adds or subtracts from there. Sometimes the numbers don't exactly correspond though.

5th Answer:
Above a certain speed, Overvoltage does need to be enabled. It usually is right around 4.6-4.7GHz, but may be higher or lower depending on the individual CPU.

6th Answer:
It is normal for the CPU voltage to fluctuate, both at idle and under load.

7th Answer:
I've seen some claim that Level 2 is best for higher overclocking. My board doesn't support LLC when overclocking, so I can't tell you for sure.

8th Answer:
Some loads will cause a CPU to require more voltage.

Note:
Going from -0.050v to -0.055v offset is actually decreasing voltage. You need to go from -0.050v to -0.045v to increase it.

Most Sandy Bridge CPUs need between 1.3v and 1.35v to be stable at 4.5GHz, so you need to increase the voltage further to be stable in Prime95. That will also help your idle crashes too.
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July 9, 2011 4:47:28 PM

Thanks LFS for your input. I made the changes with the Long Duration Maintained to 56 (max). Could you please explain to me what the changes for the 56 mean in general and to my OCing? After making the change to 56 my CPU and all 4 core temperature increase by 4*C when running Prime95 right from the start. The core temperature all started in the 60s and touch the lower 70. Before it would start in the 50s and go up to mid 60s and never touch the 70 mark. And with the offset I was changing it from -.055 to -.050 to see if that prevent BSOD.
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July 9, 2011 4:54:58 PM

For the Asrock p67 extreme4 MOBO when using the offset option there is no way that I see to increase the voltage besides increasing the offset. Am I right or wrong about that? There is the fix option, but then you can not use the offset together. With the fix option the voltage is maintained even in IDLE state so offset is better for power consumption and reduce heat?
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a c 95 à CPUs
a c 224 K Overclocking
July 9, 2011 5:33:15 PM

@ SCSandyBOC

Quote:
1st Question: First I would like to ask, what is a stable Vcore 24/7 Overclocked PC with I5-2500K SandyBridge CPU? I tried looking for the answer, but most of what I found was too old (in Jan.) and a large mix of 3.5v – 5.2v 24/7 stability.


Only a member of the extreme CPU killing squad would be applying 3.5v - 5.2v to a Sandy Bridge platform, I think you meant 1.35v - 1.52v.

Pretty much all your questions have variables, it depends on your approach to OCing the platform, there is no 100% set way of doing it, because there are so many overclocking options, that is what is so great about this platform.

We have the same motherboard, you may want to add some of the shared information in my sig, to your brain packing.

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a b K Overclocking
July 9, 2011 11:02:38 PM

Could you please explain to me what the changes for the 56 mean in general and to my OCing? After making the change to 56 my CPU and all 4 core temperature increase by 4*C when running Prime95 right from the start. said:
Could you please explain to me what the changes for the 56 mean in general and to my OCing? After making the change to 56 my CPU and all 4 core temperature increase by 4*C when running Prime95 right from the start.

The higher that number, the longer the CPU will attempt to stay at the top speed when you have all the cores loaded. If you leave it at 1, it can switch every second between the top speed and a lower speed. This is why the temps have increased a bit -- it's staying at top speed longer.

For the Asrock p67 extreme4 MOBO when using the offset option there is no way that I see to increase the voltage besides increasing the offset. Am I right or wrong about that? There is the fix option, but then you can not use the offset together. With the fix option the voltage is maintained even in IDLE state so offset is better for power consumption and reduce heat? said:
For the Asrock p67 extreme4 MOBO when using the offset option there is no way that I see to increase the voltage besides increasing the offset. Am I right or wrong about that? There is the fix option, but then you can not use the offset together. With the fix option the voltage is maintained even in IDLE state so offset is better for power consumption and reduce heat?

You can also change the voltage under load by changing the Additional Turbo Voltage setting (remember I said that ASRock boards overclock via Turbo?). I'm not sure what the Auto value is though -- you'll have to experiment with it.

And yes, Fixed mode is bad because it keeps the voltage high even when the CPU is idling at 1.6GHz speed. Offset is the mode you should use.
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July 10, 2011 2:24:24 AM

Best answer selected by SCSandyBOC.
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July 10, 2011 2:01:01 PM

I notice today when I power up my computer the led fan and computer powers on for 1 second then it goes off and then starts again within 1 second without any complication all the way to log in. Does that mean my voltage (current offset: -0.050) is not right yet for my OC? It is stable when running Prime95 for over 8 hrs and had no problem at IDLE. Please let me know if that start up issue means my computer is not yet stable (seems minor, but I want a stable OC computer). Please help.
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July 10, 2011 2:22:27 PM

I haven't tried changing the Turbo voltage setting yet, so maybe increasing the voltage (or can it be decreased?) there and changing my offset would bring better results? My current Prime95 blend torture test vcore 1.272v to 1.280v and IDLE at 0.936v - 1.064v. This is with an offset of -0.050 with no BSOD or issues that I notice except for the slight power up issue I mention on post above this one. Any advice? Thank you.
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a b K Overclocking
July 11, 2011 2:44:35 AM

That double-boot actually happens to a lot of users with Sandy Bridge systems. My system did it until the last BIOS update. I imagine it would be fixed in a future update for your system too. Or maybe Ryan has a trick up his sleeve that can fix it, beings he has the same board.
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July 14, 2011 9:21:10 PM


I recently got BSOD with message and code:
“A clock Interrupt was not received on the secondary processor within allocated time interval”
STOP: 0X00000101

Problem signature:
Problem Event Name: BlueScreen
OS Version: 6.1.7601.2.1.0.256.48
Locale ID: 1033

Additional information about the problem:
BCCode: 101
BCP1: 0000000000000031
BCP2: 0000000000000000
BCP3: FFFFF880033D7180
BCP4: 0000000000000003
OS Version: 6_1_7601
Service Pack: 1_0
Product: 256_1


Does that mean I need more voltage? So increasing my offset from -0.045 to -0.040 is what I need to do till it stops BSOD or should I increase turbo voltage instead?
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a b K Overclocking
July 15, 2011 7:12:55 AM

Either one should work, as they will both increase the voltage.
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July 15, 2011 4:22:31 PM

I read that enabling Spread Spectrum will stop the double boot. I only know that Spread Spectrum help stabilize when changing BCLK, but otherwise it should be disabled because it could have negative effects on OCing. Do you think it is fine to enable Spread Spectrum to stop double booting or is it not worth it because it may cause more issues when OCing? Please let me know what you think about this, since I am unfamiliar with Spread Spectrum.
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July 15, 2011 9:05:27 PM

Spread Spectrum varies the clock speed that the system operates at. It does this to minimize EM radiation that might interfere with nearby radios or televisions. The clock speed variation is why it's bad for overclocking -- if you're near the maximum overclock, it can become unstable. Since you're probably not near the maximum it probably won't affect the overclock.

Try it and see. If it doesn't fix the double-boot, just disable it again.
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July 16, 2011 8:16:20 PM

Today I tried to change my spread spectrum settings on the UEFI, but I am having problem getting to my BIOS. For some reason my keyboard does not power up until after it POST to the login screen. So I am unable to press F2 to enter the bios right now. I think I was in the bios before and might have change (disabled) legacy setup for USB. Would that cause my keyboard to delay power up? if so how do I get back into the BIOS?
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July 17, 2011 2:08:52 AM

I've never disabled that setting, so I don't know. I suppose it's possible.

Reset the BIOS back to defaults using the Clear CMOS button on the rear I/O panel. That should enable you to get into the BIOS again.
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July 22, 2011 4:24:12 PM

I enable Spread Spectrum and no more double boot, so that is good. I have a general overclocking question concerning the load line collaboration (LLC). When I have my LLC set to level 2 my load voltage under Prime95 is between 1.296 - 1.312. With a higher LLC (level 3) my load voltage under Prime95 is 1.272 to 1.280. Lower voltage under load is better for the system which consumes less energy and produce less head correct? Since LLC decrease voltage on load does it mean higher LLC is better? I am a little confused here because I have read that the lower LLC is better then high LLC. Could you LFS or someone knowledgeable about this enlighten me about LLC?
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July 23, 2011 12:45:09 AM

I have no idea about LLC, as the board I have makes the setting disappear whenever I overclock. I've read on other forums that level 2 gives better overclocking results.

Switching LLC settings can take an unstable system and make it stable, or it can take a stable system and make it unstable. Just do plenty of stability testing using Prime95 and if it's stable with the lower voltage leave it there.
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September 21, 2011 5:23:55 PM

Hey I recently OCed my 2500k, 4.4ghz @ 1.3v, but when I brought it down to 1.29v my cpu had a fit and ended up dead. Just a warning.

Should I have not put in a 24/7 voltage, but used offset?
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