Some quick questions on CPU overclocking

[Mini0510]

1. Does input voltage, Analog I/O voltage, Digital I/O voltage have effect on CPU temperatures?

2. Does Analog I/O voltage, Digital I/O voltage tweaking affect stability of an overclock? Or in other words, if I get a bluescreen (>4.5GHz), is it possible that it's not getting enough analog or digital I/O voltage? 

3. Even if I set the cache to auto, why do i still need to increase cache voltage when I overclock CPU (increase vcore)?

4. I have one CPU where the first chip doesn't need any cache voltage or input voltage tuning. They seem to have no effect when I increase those. It still bluescreens. It was just hungry for vcore.

[arniks8]

1. Don't know, but it can increase stability.

2. If cache ratio is set to auto then cache voltage doesn't need to be raised, vcore isn't related to cache.

3. Each chip is different and needs different voltage for stability.

BTW what's your CPU and MB?

Lowering RAM to 1333Mhz can also help for OC'ing.

[ChrisCross]

increasing the core voltage can increase the stability (no more bluescreens) and will lead to higher temperatures.

[Mini0510]

1. Don't know, but it can increase stability.

2. If cache ratio is set to auto then cache voltage doesn't need to be raised, vcore isn't related to cache.

3. Each chip is different and needs different voltage for stability.

BTW what's your CPU and MB?

Lowering RAM to 1333Mhz can also help for OC'ing.

4770K, but after overclocking, I had set the cache voltage to 1.1 even though the cache frequency is set to auto. If i set the cache voltage to auto, computer freezes during stress testing

 

and both CPUs are 4770K, using the same motherboard. I just swapped.

[arniks8]

4770K, but after overclocking, I had set the cache voltage to 1.1 even though the cache frequency is set to auto. If i set the cache voltage to auto, computer freezes during stress testing

and both CPUs are 4770K, using the same motherboard. I just swapped.

Your CPU stress test program pumps too much voltage when cache voltage is set on auto.

This might help: http://linustechtips.com/main/topic/41234-intel-haswell-4670k-4770k-overclocking-guide/

[TechHarry]

I reccommend using asus realbench or other non synthetic benchmark especially with haswell to avoid additional voltage to the cpu.

 

1. digital and analogue input voltages I think support the IMC (internal memory controller) I reccommend giving a boost to that when installing large memory kits, high frequency memory kits or overclocking the CPU and maintaining a high RAM frequency for example runnning ddr3 2400mhz RAM whilst overclocking cpu. This should make the computer more stable.

 

2.if your CPU is running at 4.5ghz oc with high speed RAM eg: 2400mhz ddr3 or a large RAM kit (over 32GB) and blue screens you can either lower the speed of your memory to reduce load on the IMC, lower the CPU frequency to reduce load on the IMC, increase DRAM voltage to increase RAM stability or as a last resort increase the analogue and digital input voltages to the cpu to increase the stability of the IMC. Don't worry too much about changing these voltages if you are new to overclocking, they make little difference to overall system stability unless you are really pushing your system.

 

3. cache frequency is separate to cpu core frequency, when increasing cache frequency you should increase cache voltage and when increasing cpu core frequency Vcore voltage shoud be raised. For stability I reccommend running your cache frequency a few hundred MHZ lower than core frequency, it has lower effect on performance and allows higher core frequencies which yeild better performance.

[Mini0510]

I reccommend using asus realbench or other non synthetic benchmark especially with haswell to avoid additional voltage to the cpu.

 

1. digital and analogue input voltages I think support the IMC (internal memory controller) I reccommend giving a boost to that when installing large memory kits, high frequency memory kits or overclocking the CPU and maintaining a high RAM frequency for example runnning ddr3 2400mhz RAM whilst overclocking cpu. This should make the computer more stable.

 

2.if your CPU is running at 4.5ghz oc with high speed RAM eg: 2400mhz ddr3 or a large RAM kit (over 32GB) and blue screens you can either lower the speed of your memory to reduce load on the IMC, lower the CPU frequency to reduce load on the IMC, increase DRAM voltage to increase RAM stability or as a last resort increase the analogue and digital input voltages to the cpu to increase the stability of the IMC. Don't worry too much about changing these voltages if you are new to overclocking, they make little difference to overall system stability unless you are really pushing your system.

 

3. cache frequency is separate to cpu core frequency, when increasing cache frequency you should increase cache voltage and when increasing cpu core frequency Vcore voltage shoud be raised. For stability I reccommend running your cache frequency a few hundred MHZ lower than core frequency, it has lower effect on performance and allows higher core frequencies which yeild better performance.

 

Thanks. RIght now, my cache frequency is set to auto. But I need to set the voltage to 1.1, or adaptive to 1.1. Otherwise, computer bluescreens when stress testing.

 

1. Is it ok if I leave the cache frequency to auto?

2. Someone sort of answered this. But why is it that I need to tune the cache voltage even though I left the cache to auto?

[TechHarry]

if the cache frequency is set to auto in the bios (which I would reccommend for someone new to overclocking because it doesn't have that much of a performance beneft and if done wrong can cause instability) leave the cache voltage on auto or what ever it is set to by default.

 

When you start overclocking I reccommend using a fixed voltage, stress testing with a non synthetic benchmark such as asus realbench and then when happy with your stable overclock switching to adaptive voltage. Something you might want to note about doing this is that when entering a fixed voltage in manual mode on most motherboards you will just enter the voltage directly EG: 1.125v (depending on processor this is just and example) where as adaptive voltages are usually an offset to the stock voltage don't enter an offset of 1.125v ontop of 1.00v for example or you will end up trying to supply the proccessor with 2.125v, depending on the motherboard this mistake will be made clear before you try to boot from it so don't worry too much. For example on asus ROG boards the value will appear in red if it is unusually high than the expected value.

[Mini0510]

if the cache frequency is set to auto in the bios (which I would reccommend for someone new to overclocking because it doesn't have that much of a performance beneft and if done wrong can cause instability) leave the cache voltage on auto or what ever it is set to by default.

 

When you start overclocking I reccommend using a fixed voltage, stress testing with a non synthetic benchmark such as asus realbench and then when happy with your stable overclock switching to adaptive voltage. Something you might want to note about doing this is that when entering a fixed voltage in manual mode on most motherboards you will just enter the voltage directly EG: 1.125v (depending on processor this is just and example) where as adaptive voltages are usually an offset to the stock voltage don't enter an offset of 1.125v ontop of 1.00v for example or you will end up trying to supply the proccessor with 2.125v, depending on the motherboard this mistake will be made clear before you try to boot from it so don't worry too much. For example on asus ROG boards the value will appear in red if it is unusually high than the expected value.

 

Yeah i did manual and found the stable voltages. Now for everyday use, I'm using adaptive.

But even though I left cache frequency to default and overclocked core frequency and raised vcore voltage, it blue screened when I ran prime95.

I have to raise the cache voltage a bit. I'm not sure why. I was hoping you have some theory/guess on it

[TechHarry]

it is likely because you are using a synthetic stress test program (prime95) which when using adaptive voltage on haswell cpu's causes the input voltage to go over your maximum input voltage (this apparently has something to do with the newer versions of prime95 and aida64 etc using AVX instruction sets on haswell and newer cpu's) this can cause temperature spikes much (10-15 degrees) hotter than a 100% load using a non synthetic benchmark. This can cause instability (bluescreens, system hangs etc). My theory would be that because the cpu core is running at faster speed than the cache (which is how it is supposed to be, it makes the system more stable) as your cpu is pulling data from your cache as fast as the cache can run because you are running a synthetic stress test (unrealistic load) it is causing a strain on your cache and giving it a bit extra voltage is keeping it stable under the extra load on the cache caused by the core frequency change. Anyway that it just a theory, probably something much more logical bit if it works it works.

[Mini0510]

it is likely because you are using a synthetic stress test program (prime95) which when using adaptive voltage on haswell cpu's causes the input voltage to go over your maximum input voltage (this apparently has something to do with the newer versions of prime95 and aida64 etc using AVX instruction sets on haswell and newer cpu's) this can cause temperature spikes much (10-15 degrees) hotter than a 100% load using a non synthetic benchmark. This can cause instability (bluescreens, system hangs etc). My theory would be that because the cpu core is running at faster speed than the cache (which is how it is supposed to be, it makes the system more stable) as your cpu is pulling data from your cache as fast as the cache can run because you are running a synthetic stress test (unrealistic load) it is causing a strain on your cache and giving it a bit extra voltage is keeping it stable under the extra load on the cache caused by the core frequency change. Anyway that it just a theory, probably something much more logical bit if it works it works.

I realize that but it's not the case. I used manual voltage when stress testing.

[runit3]

1. Does input voltage, Analog I/O voltage, Digital I/O voltage have effect on CPU temperatures?

2. Does Analog I/O voltage, Digital I/O voltage tweaking affect stability of an overclock? Or in other words, if I get a bluescreen (>4.5GHz), is it possible that it's not getting enough analog or digital I/O voltage? 

2. Even if I set the cache to auto, why do i still need to increase cache voltage when I overclock CPU (increase vcore)?

3. I have one CPU where the first chip doesn't need any cache voltage or input voltage tuning. They seem to have no effect when I increase those. It still bluescreens. It was just hungry for vcore.

1. Input -minor impact. Analog I/O -margin of error +/- .1-.2v, Digital I/O (system agent?) I haven't seen this setting on Z97. This is in relation to CPU core temps, I/O may affect package temps to a greater extent. I've never needed to mess with anything other than input voltages on Z97...X99 is another story >_>

2. Not unless you're going into extreme OC's past 1.5v and on phase or LN2. Again, Z97 specific.

3. I've never experienced the problem you describe, then again I always OC my cache to within a 1:1 (if possible) or -2-300MHz off my core clock. Cache voltages follow a similar trend. My best guess would be that for your particular CPU locking in the cache is necessary for stability.

4. Every chip is different, this is to be expected.