OC of i7 975 - should I be concerned about voltage? And can I push more?

[flux104]

I have an older x58 based system, Asus P6T mobo, I'm trying to breathe new life into with a few inexpensive upgrades. I just put in an i7 975 Extreme Edition 3.33 GHz and am OCing to 4123 GHz with a 31x multiplier. It is stable with good temps (37-45 C).

Question 1: CPU-Z reports the core voltage 1.424v. The CPU specs says the voltage range is .8 - 1.375. should I be concerned it's running out-of-range? voltage is set to Auto in the Bios.

Question 2: When I go to 32x multipler (4256 GHz), I start getting stability issues (BSOD). But being temps are okay I'm thinking I should be able to push it further. Any tips on how I can get more out of it?

It has pretty good cooling with a big after market heat sink and fans (air though), and case has real good ventilation. It was a Vigor Gaming machine designs for performance/overclocking.

Thanks for any info or tips.

Best,
Jack

 

[Baumy15]

I have an older x58 based system, Asus P6T mobo, I'm trying to breathe new life into with a few inexpensive upgrades. I just put in an i7 975 Extreme Edition 3.33 GHz and am OCing to 4123 GHz with a 31x multiplier. It is stable with good temps (37-45 C).

Question 1: CPU-Z reports the core voltage 1.424v. The CPU specs says the voltage range is .8 - 1.375. should I be concerned it's running out-of-range? voltage is set to Auto in the Bios.

Question 2: When I go to 32x multipler (4256 GHz), I start getting stability issues (BSOD). But being temps are okay I'm thinking I should be able to push it further. Any tips on how I can get more out of it?

It has pretty good cooling with a big after market heat sink and fans (air though), and case has real good ventilation. It was a Vigor Gaming machine designs for performance/overclocking.

Thanks for any info or tips.

Best,
Jack

ive seen people say no more than 1.45v into those chips.

 

[rhysiam]

How are you setting the voltage? Are you doing that yourself in the BIOS? If so, did you set it that high? Have you done all the usual preliminary steps of disabling power saving features, etc (I can't remember what they were called on that older platform off the top of my head). Google some guides if you haven't done that.

That voltage is very high for a 24/7 OC, I wouldn't go that high myself.

It's not just temps that limit an OC. A CPU is made up of millions (/billions) of transistors which are like electrical gates which open and close. The higher the frequency the faster you need those gates switch states (from open to closed or vice versa). As you up the frequency there comes a point where the transistors just can't change states quickly enough, that results in system lockups or BSODs. Thankfully it doesn't physically damage the chip though... just breaks whatever software it's trying to run.

Upping the voltage effectively speeds up the ability of the gates to change states (you can think of that like upping the power on the magnets which pull the gates closed or push them open). But higher voltages result in more power and heat.

It's these high voltages that can, if pushed to high or for too long, physically damage the CPU. So what you're trying to do when you OC is find a point where the frequency is as high as possible, with the voltage as low as possible, but the system is still stable. You can usually OC the CPU a fair way with very small voltage increases. But then you'll find as you approach the limit of the CPU, even small increment in frequency requires a much larger injection of voltage to stay stable. You want to find the point on that curve that makes sense.

I like how Ian Cutress from Anandtech approaches it. He bumps frequency, then ups voltage in small increments until the system is stable... rinse and repeat. Have a maximum voltage and temperature in mind before you start. He builds a table as he goes with CPU Volts and Frequency so you can clearly see where the voltage starts to take off for tiny frequency increments and the OC is no longer worthwhile.
You can see an example in the 6700K review here: http://www.anandtech.com/show/9483/intel-skylake-review-6700k-6600k-ddr4-ddr3-ipc-6th-generation/6

 

[flux104]

How are you setting the voltage? Are you doing that yourself in the BIOS? If so, did you set it that high? Have you done all the usual preliminary steps of disabling power saving features, etc (I can't remember what they were called on that older platform off the top of my head). Google some guides if you haven't done that.

That voltage is very high for a 24/7 OC, I wouldn't go that high myself.

It's not just temps that limit an OC. A CPU is made up of millions (/billions) of transistors which are like electrical gates which open and close. The higher the frequency the faster you need those gates switch states (from open to closed or vice versa). As you up the frequency there comes a point where the transistors just can't change states quickly enough, that results in system lockups or BSODs. Thankfully it doesn't physically damage the chip though... just breaks whatever software it's trying to run.

Upping the voltage effectively speeds up the ability of the gates to change states (you can think of that like upping the power on the magnets which pull the gates closed or push them open). But higher voltages result in more power and heat.

It's these high voltages that can, if pushed to high or for too long, physically damage the CPU. So what you're trying to do when you OC is find a point where the frequency is as high as possible, with the voltage as low as possible, but the system is still stable. You can usually OC the CPU a fair way with very small voltage increases. But then you'll find as you approach the limit of the CPU, even small increment in frequency requires a much larger injection of voltage to stay stable. You want to find the point on that curve that makes sense.

I like how Ian Cutress from Anandtech approaches it. He bumps frequency, then ups voltage in small increments until the system is stable... rinse and repeat. Have a maximum voltage and temperature in mind before you start. He builds a table as he goes with CPU Volts and Frequency so you can clearly see where the voltage starts to take off for tiny frequency increments and the OC is no longer worthwhile.
You can see an example in the 6700K review here: http://www.anandtech.com/show/9483/intel-skylake-review-6700k-6600k-ddr4-ddr3-ipc-6th-generation/6

Thanks for the info. To answer your questions:
In the BIOS, the CPU voltage was set to Auto, and so it was auto-ing itself to 1.424 (how it came to that, I don't know). I've now manually adjusted it to be lower. I tried 1.275 then 1.285 and for both settings I got BSOD right after POST. At 1.3, it booted up and appears to be stable (for now, although I haven't stressed it much).

The settings I changed to get the OC:
AI Overclock Tuner set to Manual
Intel SpeedStep Tech = Disabled (from enabled)
CPU Ratio Setting = 31 (from Auto)

Thanks,
Jack

 

[rhysiam]

Yeah, you don't want auto voltage.

You'd be lucky if 1.3V is enough for 4.2Ghz +, I think you'll get BSOD on a stress test and require a bit more voltage, but for sure try it and see. Then bump the voltage until it's stable.

I'm not claiming to be an expert on how voltage affects the life of a CPU, and others will have different opinions to this (and verly likely more informed opinions at that), but here's my perspective for what it's worth: If I want to keep a CPU a long time I wouldn't go much over 1.35V, but if I was in the process of saving for an upgrade and just wanted to squeeze as much as I could, I'd happily go to 1.4V. Above that (IMHO) risk goes up rapidly, so I'd only do it if I really didn't care about the CPU anymore.

 

[flux104]

Thanks Rhysiam. It's stable now at 4.123 GHz with voltage manually set to 1.31. I can't seem to push it further without upping voltage to 1.35+ so I'll leave it as is.

Jack