CPU/NB voltage

[BackwoodsBob]

I posted a thread with some pictures and never got a single answer.
So I am going to try a different angle.
What is CPU/NB voltage and what does it do?
I get that CPU/NB is... cpu/north bridge. I would bet that it has something to do with supplying the right voltage to the bus.
How do I decipher that BEFORE I fry something?
Maybe if I post my questions one by one I can get some answers.
TIA!

 

[Zach_01]

On those CPUs the "CPU NB" is the part of the CPU that contains the IMC, Integrated Memory Controller. This CPU NB connects the CPU cores to RAM and board chipset (NB) through HT Link.
HT Link is the BUS between CPU and the board NB=chipset.

Dont confuse CPU NB with the Northbridge of the board. Its different things.



They have the same name (Northbridge) because on older systems the memory controller was on the board NB.

 

[BackwoodsBob]

On those CPUs the "CPU NB" is the part of the CPU that contains the IMC, Integrated Memory Controller. This CPU NB connects the CPU cores to RAM and board chipset (NB) through HT Link.
HT Link is the BUS between CPU and the board NB=chipset.

Dont confuse CPU NB with the Northbridge of the board. Its different things.

View attachment 182293

They have the same name (Northbridge) because on older systems the memory controller was on the board NB.

So its not bus speed voltage?
Glad I asked.
It has to do with ...
Ok maybe I still don't get it. I get that it is NOT northbridge.
I get that it has something to do with HyperTransport. Which IIRC, is the physical thing that links the cores to the RAM. It has to do with how the cores communicate with the RAM... Right?
I googled HT and got an even more confusing answer.
Can you dumb down what it is please? What it does and how it works? I used to know this stuff, or had a class on it that I didn't quite understand (more likely)

 

[Zach_01]

You see the pic I posted? CPU is connected to RAM, without the board chipset in the middle. CPU NB is the part of the CPU that contains the MemoryController. CPU NB is inside the CPU, right next to cores. No HT link for CPU NB <-> RAM.
HT link is the connection between CPU NB and the board NB.

 

[BackwoodsBob]

You see the pic I posted? CPU is connected to RAM, without the board chipset in the middle. CPU NB is the part of the CPU that contains the MemoryController. CPU NB is inside the CPU, right next to cores. No HT link for CPU NB <-> RAM.
HT link is the connection between CPU NB and the board NB.

View attachment 182303

So the CPU NB physically lives on the CPU?
If I understand correctly, this is how the CPU physically connects to the RAM through the IMC.
Is this right?
Either way, what does changing the voltage here do?
Be prepared for about 15 more questions concerning voltage and what it does.
I have looked for this info, high and low. Like everything else, it takes a conversation to gain understanding.

 

[agent_x007]

Short answers :
1) Why it's here : DDR3 can be powered by A LOT more than Vcore, so - a "barier" is need to prevent damage from different voltage (example : Nehalem/Core i7 9xx IMC). It's probably also the base for "CPU/NB" naming (since it's the "NB" portion of "CPU").

2) At this point, and to keep things easier, CPU designers use seperate clock speed for IMC (usually called "NB Frequency" under CPU-z's tab "Memory"). If you want to make faster trips to RAM, beyond timings and frequency of said RAM, overclock of said "NB Frequency" may be required.
Higher frequency = less stability at the same voltage, so you get a voltage control for it to make it stable again.

 

[BackwoodsBob]

Short answers :
1) Why it's here : DDR3 can be powered by A LOT more than Vcore, so - a "barier" is need to prevent damage from different voltage (example : Nehalem/Core i7 9xx IMC). It's probably also the base for "CPU/NB" naming (since it's the "NB" portion of "CPU").

2) At this point, and to keep things easier, CPU designers use seperate clock speed for IMC (usually called "NB Frequency" under CPU-z's tab "Memory"). If you want to make faster trips to RAM, beyond timings and frequency of said RAM, overclock of said "NB Frequency" may be required.
Higher frequency = less stability at the same voltage, so you get a voltage control for it to make it stable again.

If I understand you, ddr3 RAM can be subjected to excess voltage that "spills over" from...somewhere, and this extra voltage control prevents that somehow. What it does is help create stability at higher frequencies.
Is that right? I have 2133Mhz RAM. If I didn't have this extra voltage control, my computer would be crashie.
I have mt memory set to the XMP profile. I am betting I need to keep this voltage on Auto?
Can you explain what CPU VDDA voltage is?