Vcore voltage not what I set in BIOS - i5 3570k on Gigabyte Motherboard, help!

[straati]

Hi guys, first post here on Tom's Hardware.

I replaced my Asus GeForce 670 with a Asus 1060 6GB OC on black friday, and since I'm noticing games as The Witcher 3 and Battlefield 1 is pretty CPU-dependent, I want to eliminate the bottleneck (which is my CPU) so that I can make sure my new GPU is flexing it's muscles. I'm using MSI Afterburner so that I can see what gets to 100% load first, and it's almost always my CPU.

So, I'm an amateur when it comes to overclocking, and since I've invested in some good Noctua cooling fans - both for my chassis and my CPU - I thought it wouldn't be too much to ask to get a "small" overclock to about 4.2 or 4.3 GHz.

I've read some guides, and I'm using Prime95 for torture-testing, Core Temp for monitoring my temperatures and CPU-Z to monitor Vcore. My problem is this: when I set a fixed Vcore voltage in my BIOS, it's not what my CPU gets under 100% load in CPU-Z. What I've done is this:

* Disabled the Turbo-function
* Set the clock ratio to 42
* Set LLC to Extreme (highest option)
* Set Vcore to 1.195 V

When I run Prime95 on "Small FFTs" CPU-Z is showing a Vcore of 1.224 V. Why? I can't overclock knowing Vcore isn't what I set in BIOS. What do you guys think? I'm new to overclocking so it isn't impossible that I've forgotten or missed something.

My system:
* Gigabyte GA-Z77X-D3H Motherboard
* Intel i5 3570K 3.40 GHz
* Asus GeForce 1060 6GB DUAL OC
* 4x Corsair Vengeance DDR3 1600 MHZ CL9 (16 GB tot)
* Windows 10

Thanks in advance

 

[vMax]

This is becouse of your LLC setting which will provide additional voltage as you have set it to Extreme..Extreme tends to push the voltage higher. Bring that down a touch. I had the same problem and reduced from Turbo to High (Gigabyte Z370 motherboard has auto, medium, high and Turbo) and had much better control, though still a tad higher.

The difference on yours does not seem to bad..just 20mv's but see what happens if you drop it one notch down from extreme and check stability at the new LLC setting.

 

[straati]

This is becouse of your LLC setting which will provide additional voltage as you have set it to Extreme..Extreme tends to push the voltage higher. Bring that down a touch. I had the same problem and reduced from Turbo to High (Gigabyte Z370 motherboard has auto, medium, high and Turbo) and had much better control, though still a tad higher.

The difference on yours does not seem to bad..just 20mv's but see what happens if you drop it one notch down from extreme and check stability at the new LLC setting.

Well, I've tried countless of BIOS-settings, like different values on the LLC and it didn't help. As far as I'm concerned, LLC prevents vdrooping (when the voltage fluctuates under heavy load?) and didn't really help with my issue no matter what I tried. The fact that I couldn't control what voltage that supplied the CPU during load is a case-killer for me.

Anyhow, I updated from BIOS version 18g to 18i and guess what, I tried the same settings as before (which I wrote in my first post) except for lowering LLC 1 notch and the base clock from 42 to 40. Now, the voltage in CPU-Z shows 1,188 V and I put 1,195 in BIOS. A 7 mV difference maybe isn't so bad? I'm not sure of what I should expect, since this is the first time it seems to "work".

How much difference is it usually from the Vcore you set in BIOS from what you get in CPU-Z under 100% load from Prime95? Is a 7 mV difference OK?

 

[vMax]

7 mv is more than good...It is a very small difference and if that is the max difference you are seeing, I would say you are in a good space with regards to the overclock and moving on. I personally am happy with an overclock so long as I do not exceed 1.3v...I know we can safely go higher to around 1.35 but I am a bit of a wimp and worrier and do not like to go that far for a daily use PC. You on the otherhand are well within parameters and in fact at the better end in terms of vcore required. The difference above and below, especially at 7mv is good as far as I can see..

 

[straati]

7 mv is more than good...It is a very small difference and if that is the max difference you are seeing, I would say you are in a good space with regards to the overclock and moving on. I personally am happy with an overclock so long as I do not exceed 1.3v...I know we can safely go higher to around 1.35 but I am a bit of a wimp and worrier and do not like to go that far for a daily use PC. You on the otherhand are well within parameters and in fact at the better end in terms of vcore required. The difference above and below, especially at 7mv is good as far as I can see..

Wow, thanks. I didn't know that. However, I'm not closing this case yet, knowing my luck, things will soon go sour again. Okay, so I picked a frequency of 4.00 GHz to start my overclock with (since 3.80 is the stock turbo-frequency, I thought a 200 MHz jump wouldn't be so bad), and since 1.195 V for 4.00 GHz is pretty high, I reckoned it's a "safe" start.

I ran 10 min of Prime95, monitored the Vcore and my temps, everything went fine. I thought, now I can lover the voltage 5 mV, and so I did. I started Prime95 (it's running now as I write), and the Vcore voltage is STILL 1.188 V as when I put Vcore on 1.195 before. Why hasn't the core voltage changed since I lowered it in BIOS? Is 5 mV too little to make a difference? How big voltage-increments should I take when lowering/raising the voltage in relation to clock-speeds? 10 mV instead of 5 mv?

 

[vMax]

Yep, 5mv may be to small, but I still like to go down in 5mv steps...keep going..

 

[straati]

Yep, 5mv may be to small, but I still like to go down in 5mv steps...keep going..

I kept going with 5 mV and it seems like when I've reduced 10 mV in BIOS, I'd see a decrease in voltage in CPU-Z. Since my last post I've successfully decreased my Vcore from 1.195 to 1.145. I'm running at least 10 mins in P95 before lowering an additional 5 mV. However, at 1.145 I got a BSOD after approx. 10 minutes, so I guess I've hit the "bottom". I raised Vcore by 5 mV (back to 1.150 V) and now I'm running Prime95, thinking about what my next step should be. I'm guessing it's time to raise the clock ratio from 40 to 41...?

 

[vMax]

Sufferin sucatash!!!!...I could not get my 6700K and now my 8600K anywhere near that...Yep its time to start moving upwards on the clock ratio.

 

[vMax]

I just read a review of your CPU...Goes back a bit, but they say it is another near 5GHz cpu and rate it highly:

http://www.techradar.com/reviews/pc-mac/pc-components/processors/intel-core-i5-3570k-1077183/review/2

 

[straati]

Sufferin sucatash!!!!...I could not get my 6700K and now my 8600K anywhere near that...Yep its time to start moving upwards on the clock ratio.

Oh! What clocks are you running at?

I stayed at 1.150 V and increased my clock ratio to 41 and couldn't get past the BIOS-screen without the entire system crashing up on me. I had to raise Vcore to 1.175 before I could get in to Windows again. I restarted and set my Vcore to 1.180 V and now I'm running Prime95 again.

So increasing 100 MHz needed (at least) a 30 mV increase in Vcore? Is this normal? Maybe every 100 MHz increase exponentially (or close to) increases the strain and/or stress of the CPU?

 

[vMax]

On my 6700K, I had to run a 1.32vcore to get stable at 4.5GHz!!!! luckily on the 8600K, I am stable at 1.278v at 4.9GHz...5GHz needs over 1.338v!! cant live with that.

 

[straati]

On my 6700K, I had to run a 1.32vcore to get stable at 4.5GHz!!!! luckily on the 8600K, I am stable at 1.278v at 4.9GHz...5GHz needs over 1.338v!! cant live with that.

Ok. Nah, 1.1338 seems a tad to much. I've successfully overclocked my CPU to 4.2 GHz with a Vcore at 1.225 V. It seems a bit much, and my CPU is starting to hit over 70 C during Prime95. I guess if I start pushing for 4.3 GHz my CPU will need at least 1.265 V which will push my temperatures even further. What is the optimal secure max-temperature? 85 C?

 

[vMax]

Sorry about the late response....at work.. That seems a bit high on the temps for the speed you have. What CPU cooler are you using? I have to admit, I use a AIO 360mm radiator with 3 X 120 fans which keeps things cool even under p95 load at under 70 Degrees c at 4.9GHZ

 

[vMax]

On my 6700K, I had to run a 1.32vcore to get stable at 4.5GHz!!!! luckily on the 8600K, I am stable at 1.278v at 4.9GHz...5GHz needs over 1.338v!! cant live with that.

Ok. Nah, 1.1338 seems a tad to much. I've successfully overclocked my CPU to 4.2 GHz with a Vcore at 1.225 V. It seems a bit much, and my CPU is starting to hit over 70 C during Prime95. I guess if I start pushing for 4.3 GHz my CPU will need at least 1.265 V which will push my temperatures even further. What is the optimal secure max-temperature? 85 C?

Going over 80 degrees C is too much for me but still okay...just!! I personally try not to go into the 80's c degrees...70's I can live with as I know that most of my normal use like Games, a little video edditing ect. will never push my temps past 50 to 60 C degrees anyway only bench testing takes it near or into the 70's...

 

[straati]

Sorry about the late response....at work.. That seems a bit high on the temps for the speed you have. What CPU cooler are you using? I have to admit, I use a AIO 360mm radiator with 3 X 120 fans which keeps things cool even under p95 load at under 70 Degrees c at 4.9GHZ

No worries, I'm quit busy because of work myself (hence my late response). I'm using a Noctua NH-U12P SE2-cooler on my CPU, which is a push-pull type of cooler with two fans. On my chassis I have two Noctua NF-P12 120mm in the front and one Noctua NF-A14 FLX 140mm in the back. So the air-flow goes in the fron through the two 120mm fans, through the push-pull CPU-cooler and out in the back through the 140mm fan.

I replaced the thermal paste and cleaned my CPU-cooler today and disconnected the ULNA's (ultra low noise adapter) from all my fans which operated at 900 rpm before and 1300 rpm now. With my current overclock, my idle-temperatures is around 30 C and during 100% load in Prime95 it reaches over 70 C.

Now I know Ivy Bridge-chips are running pretty hot, but I didn't know they were this hot.