CPU VID Does not affect Overclocking.

[Emphacy]

I've known for a long time what CPU VID was, how to find it and why people say it effects the ability to overclock a CPU.

Thus, today, I decided to find out how VID (Voltage Identification) really worked and if possible how you change it.
It turns out that CPU VID isn't as simple as everyone thinks, and that a CPU doesn't just have 1 voltage identification level, it in fact, has 6 which vary between motherboards and systems.

Here's some information I found on another forum, some of which is said to be directly off the Intel website, but you need an account to view the databases.

The VID is hardcoded into each individual cpu, but it's not just one number; it's a range of 6 different VID levels and these levels are specific to each individual CPU. VID is not static and changes with power requirements. VID can fluctuate almost constantly to try to maintain the level programed into it during manufacturing.

I was just curious what CoreTemp actually reports, is it reporting the VID being used at the time, max VID, etc? VID is read from a sense line off one of the cpu pads, it seems like CoreTemp would have to be reading whatever VID level is in use at that time.

Here's another quote in the same place which is direct from Intels website. I tried to access any information myself, but it view it, it asked me to login.

Individual processor VID values may be calibrated during manufacturing such that two devices at the same core speed may have different default VID settings. This is reflected by the VID Range values provided in Table 5.

The processor uses six voltage identification signals, VID[6:1], to support automatic selection of power supply voltages.

The processor provides the ability to operate while transitioning to an adjacent VID and its associated processor core voltage (VCC). This will represent a DC shift in the load line. It should be noted that a low-to-high or high-to-low voltage state change may result in as many VID transitions as necessary to reach the target core voltage.
Transitions above the specified VID are not permitted. Table 5 includes VID step sizes and DC shift ranges. Minimum and maximum voltages must be maintained as shown in Table 6 and Figure 1 as measured across the VCC_SENSE and VSS_SENSE lands.

This explains why my Q6600 despite it's low VID of 1.2V on my system still doesn't overclock very well, in fact, after 3GHz it's unstable. Must be my motherboards voltage regulators which also explains why you can clock better on some motherboards, than on others.

What do you guys think?

 

[Emphacy]

Not all CPU's are created equal. Some require more voltage than others. All the VID does is tell the motherboard/PSU how much juice to give it.

As said above, generally speaking the lower the default voltage, the better the chip tends to overclock which makes perfect sense if you think about it.

You never actually know what the CPU's lowest VID is though. CoreTemp will only tell you the current VID in use, not the minimum.

And since this ranges from motherboard to motherboard, you will never know the CPU's lowest VID and since the same range of 6 VID levels are present in each CPU how do you know which one the CPU will choose in your setup.

It may need a 1.2V VID in one persons PC and a 1.1 in someone elses, and since this is effected by a motherboards voltage regulation ability it could be any VID in the 6:1 range.

 

[Emphacy]

No.

Each individual CPU only has 1 and it's fixed and doesn't change regardless of motherboard or other components.

They may, as stated, have several VID's for their different power states, ie when running slower using Speedstep, etc, but for the purposes of this discussion it's the main full speed/full load VID that's important.

VID = that particular CPU's default stock voltage.

Well thanks for clarifying this, and to others above, this is why I asked. My Q6600 isn't a good clocker, so checked out VID.
Is 1.3125V a low VID for this kind of processor? It could either be down to the VID or my Northbridge getting a bit toasty/ my cheap motherboard like said above.

Thanks for the input and to clarify things.

 

[Emphacy]

MSI P43 Neo-F Motherboard at current, wanting to go for a Rampage Extreme if I can find one...

The memory is only 800MT/s with a maximum clock of 920MT/s so I always set the ratio to 1:1.25 so memory is at 667MT/s before overclocking. I then clock the Q6600 to something like 3.3 when the RAM reaches 915MT/s.

It boots up fine and all but after about 5/10mins of gaming is BSOD's.

 

[Emphacy]

Im guessing 3.4ghz on a q6600 would have no bottlenecking issues with the latest graphics cards?

Pretty much, the Q6600 is still a powerful enough processor even today and shouldn't affect even the highest-end GPU's.