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What are all haswell voltages, what they do, and what is their approximate defaults?

post #1 of 3
Thread Starter 
I noticed my motherboard (ASRock z97 Extreme4) has lots of options about voltages...

Not only that, it has a staggering amount of voltage sensors available, some that people still have no idea what they do (HWinfo64 people for example still have 3 or 4 sensors to figure out, they are seemly valid but people are not sure what they do).


But every time I look into information about this, for several reasons (that I will write about shortly), I get into issues.


1. Lots of outright outdated information, usually from Sandy Bridge era, including with threads here on this forum with people flaming each other for getting terms wrong, saying VCCIO is not VCCIO and whatnot.

2. Lots of people saying: "Don't care about it, just up that particular voltage to get the OC you want", and no explanation.

3. Lots of "they change from processor to processor, os it is pointless to know about anyway."


Still, I do want to know, for also three reasons:

1. I am very curious, even nagged (and got with success!) the Super I/O chip manufacturer to give me its datasheet.

2. I might want to get the best performance as possible by doing ridiculous amounts of tweaking of all parts, including CPU, RAM, mobo, GPU, HDD... and everything else I can think of. (floppy drives? I wonder if anyone ever OCed a floppy drive).

3. I am curious about my current PSU, it is crap enough to seemly result in bad performance, but good enough to not be dangerous (ie: it doesn't explode, catch fire or cause dangerous overvoltage), and seemly there is a correlation between various voltages and CPU and GPU power protection throttling.



So I wanted to know what are all voltages on haswell, and their approximate defaults (ie: I know each processor has its own values set in the factory, but OC people still know the most common averages, or at least the most common mininum and maximums).
post #2 of 3



This is the haswell voltage table provided by this overclocking guide from here:
http://www.overclock.net/t/1401976/the-gigabyte-z87-haswell-overclocking-oc-guide

Now I am going to give you my safe / recommended voltages for each of these. I have done overclocking on multiple haswell-refresh CPUs so I'm going to go through these one by one as said:

VRIN Override (Input Voltage / Eventual Voltage): I will only go as high as 2.1v. 1.7-1.95v is generally enough.

VCore (Core Voltage): You will most likely hit a temperature barrier on the CPU (meaning the CPU will end up throttling first than getting to a too high CPU voltage. The CPU voltage range I'm comfortable with is 1.2v-1.35v (I may go 1.40V personally for benchmarking purposes).

CPU Ring Voltage (Cache Voltage): You generally only need around 1.1v-1.250v.

System Agent Voltage (VCCSA): I only go as high as 0.15V+ offset. Can help stabilize memory overclock.

CPU I/O Analog / Digital (VCCIO): Stick to what the table says.

PCH Voltage: I generally just leave this on auto. Don't really need to configure at all unless in certain scenarios.

DRAM Voltage: I do 2400MHz overclocks on 1.65v-1.70v. Ram voltage only needs to be changed usually when overclocking memory. Best to leave it at stock ram voltages.

The table basically mostly says what I said.
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Gaming Computer
(19 items)
 
   
CPUMotherboardGraphicsRAM
Intel Core 2 Quad Q6600 Asustek P5Q-PRO Nvidia 9800 GTX+ Kingston DDR2 8gb 
Hard DriveOptical DriveCoolingOS
Western Digital 1 TB Pioneer Noctua NH-U9B Windows 7 Ultimate 64-bit 
MonitorKeyboardPowerCase
Dell Monitor Logitech G110 Antec 750W Thermaltake Aluminium Old Case 
MouseMouse PadAudio
Logitech G500 Gaming Mouse Generic Mousepad Soundblaster 5.1 VX 
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post #3 of 3
Thread Starter 
Thanks smile.gif

Did some measuring here, I disabled C states, downthrottling, and per-core throttling, the mobo set both core and cache to 39x (ad 100 blck)

voltages are all on auto, except I disabled "adaptative"

idle voltages:

CPU Input: 1.744 nice, headroom there smile.gif
Core 1.140 headroom there too smile.gif
Vcore offset: 0
Cache offset: 0
System Agent offset: 0.3V frown.gif (result of my strange EVGA ram?)
Analog I/O: 0.149V :/
Digital I/O: 0.199V :/
DRAM: 1.650V (ram XMP setting)
PCH 1.05: 1.082
PCH 1.5: 1.506


The "PCH" and ram controller ones (not the DRAM itself one) that were confusing me, now that I know what they are, it makes slightly more sense.

The seemly bad ram voltages might be my mobo compensating my crap PSU (2 12v rails, only 4 pin 12v connector to the mobo, 12v drop to 10v after 5 minutes of OCCT PSU test with everything stock)

I will read my logs (I make lots of CSV logs of my tests) and see how much voltages vary under load.
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