MSI Z77A-G45 Gaming Review

Using water in a very cold room...

That room would have to be your unheated garden shed in the continental Antarctic winter at
-60 C mate. And even then I'm not sure about 5.5. And you couldn't use water anymore due
to freezing problems.

Don't ask me why you'd have a garden shed in the Antarctic though :lol:
 
That room would have to be your unheated garden shed in the continental Antarctic winter at
-60 C mate. And even then I'm not sure about 5.5. And you couldn't use water anymore due
to freezing problems.

Don't ask me why you'd have a garden shed in the Antarctic though :lol:

Why would you have a garden shed in the Antarctic?


But yeah, like the guys here are saying, an overclock like that with regular watercooling is not going to happen, not even in a 'cold room'.
 
Well then, I ask you the question how bad is the thermal conductivity of the chip? How many watts are you pulling at 4.8GHz? What temperature do you get at the base of the heatsink?

It should be pretty easy to estimate the power draw of the chip at 5.5GHz if you know the voltages needed relative to 4.8GHz. Then you can estimate the TJ from the thermal conductivity relative to 4.8GHz and lets say 4.0GHz.

Anyway, so you'd say I can get to the thermal limits of the chip without frying the power delivery or vreg?
 
Well then, I ask you the question how bad is the thermal conductivity of the chip?

Since the chip is physically mostly silicon with a little metal and other bits, and the thermal
conductivity of Si is ~149 W·m−1·K−1, it will probably be around that.
However, the chip is the heat source and only conducts its own heat outwards, and I
have yet to see how this information helps you overclock.

How many watts are you pulling at 4.8GHz?

Depends on your voltages.

What temperature do you get at the base of the heatsink?

Depends on your voltages.

It should be pretty easy to estimate the power draw of the chip at 5.5GHz if you know the voltages needed relative to 4.8GHz.

No. For one thing, each chip is different, requiring different voltages for different clocks.
Secondly, the correlation between required voltages and reachable clock speeds is
non-linear, thus making predictions very tricky.

EDIT:
To clarify: You might get 1.5x the clock speeds for 1.3x higher voltage, but to get
1.6x clock speed you might need 1.7x higher voltage. And that might just be for
one single chip, on another chip you might get 1.5x/1.4x and 1.6x/1.8x. I know
these numbers are not realistic, but they should get the point across.
/EDIT

Then you can estimate the TJ from the thermal conductivity relative to 4.8GHz and lets say 4.0GHz.

It's an interesting idea, but doing this with any sort of reliability would require you to
properly investigate the above mentioned relationship and several other factors in high
volume sample tests on a large scale with great precision, then doing some serious
academic statistical analysis on that sample.

Basically, you would need to investigate all those ugly, non-linear relationships and
how they behave over the clock, power and voltage spectrum.

EDIT:
And even that would only enable you to predict anything with limited reliability.
However, provided your sample was large enough and you did your statistical
analysis right, you would be able to assess how reliable/unrealiable your
prediction would be.

Also: The thermal conductivity of the chip would not change over the clock spectrum.
Thermal conductivity has some dependence on temperature, however in the
temperature spectrum we're talking about here that's probably negligible.

I fail to see how changing clock speed in and of itself would influence the chip's
thermal properties. And it also won't be changed by changing the voltages, just
as a side note. The thermal conductivity of silicon is relatively constant in the
environment we're talking about here.
/EDIT

Anyway, so you'd say I can get to the thermal limits of the chip without frying the power delivery or vreg?

You will most likely fry your CPU long before you will ever fry the M/B power delivery
components.

On another note: Did you put the OC Noob thing in your sig or was that a "gift"? ;)

EDIT:
The only way I know of (and if there are others, somebody please
enlighten me, I'm a curious person) to get an IB chip to 5.5 GHz is with some serious
sub-zero cooling. Dry ice, liquid nitrogen and that stuff. No amount of conjecture,
guesstimates or clever thinking will get you around that afaik. It's just basic physics
(well, thermodynamics, really).
/EDIT
 
Last edited:
OK, I do suppose you are right about the reliability, but I doubt that you'd have much trouble calculating the power needed within 10% of most realistic situations...

The reason I mentioned the thermal conductivity of the silicon is because of a combination of the as I guessed relatively low thermal conductivity of silicon, and the fact that most of the junctions (which I'd think i can safely assume is where over 3/4 of the heat comes from) are not right at the surface of the chip, that is partially explained by the fact that most people get temps on the heatsinks much lower than the temps on the junctions.

Again, I'll see what I can pull out of the chip with some seriously bawlzy overclocking when I get my rig done... (need to wait for christmas that means)

No it was not a "gift", rather an appropriately stolen idea.

Anyway, thanks for giving me the answer to my original question :D

And a quick question (that doesn't really belong here) how does SB OC compared to IB? I have a hunch that IB chips are getting breakdowns at higher voltages, which is why the temps rocket up above a very defined voltage.
 
Last edited:
And a quick question (that doesn't really belong here) how does SB OC compared to IB? I have a hunch that IB chips are getting breakdowns at higher voltages, which is why the temps rocket up above a very defined voltage.

Again you are really way off the mark here. The temps are different because of the TIM used to mount the IHS to the actual cpu.

Overclocking is nearly ALWAYS limited by the CPU itself, the motherboard and the actual users experience come after.

ie: for example every 2700K and 3770K Ive ever touched, used, had has overclocked different to the last one.
 
Well, if the TIM has a higher thermal resistance I would think that the temperature curves would be similar, not with a spike around 1.4 volts (or wherever you get the sharp rise). That sharp rise AFAIK didn't appear as drastically on the SB chips.

True the TIM and IHS have an effect, but not one this huge. And I doubt the spike would go away if you mounted a heatsink directly to the chip.

The thing is that on the 22nm manufacturing process the transistors are so small that they may start getting breakdowns across the transistors. The leakage current has a low enough voltage not to cause errors, but it still is there and generates a lot of heat. I am not familiar with the gate level architecture of the chips, but either across the gate or between different transistors you might get breakdowns and basically short circuits. I would not be surprised if NVidias Maxwell chips will suffer from the same problem when they move to 20nm.

You are making me want to buy a 2500k and a 3570k so I can compare the two :S
 
True the TIM and IHS have an effect, but not one this huge.

Oh it does have an effect, and a rather significant one at that.

And I doubt the spike would go away if you mounted a heatsink directly to the chip.

Which spike are you referring to? The non-linear increase in required voltage for a certain
gain in clock speed or the parabolic increase in heat output in relation to the voltage?

You are making me want to buy a 2500k and a 3570k so I can compare the two :S

Again, the problem is in the sample size. You'd need to buy a lot of chips to get any sort
of reliable data. You could get a 2500k that does not go beyond 4 GHz, and a 3570k that
easily gets to 4.8, or vice versa. You'd need to test a lot of chips to even this out and enable
you to draw any reliable conclusions.

Not that anyone's stopping you ;)
 
Well, I saw that the SB CPUs were much more consistent in getting over 5GHz.

The spike I am referring to is the one that appears when you turn up the voltage, where there is a very sharp increase in temperature as you go over a certain voltage. From what I saw most SB chips don't have one that sharp, while IB chips all get it around 1.4V (If I remember correctly, it might be higher).

Of course you could get outliers that don't give as much or give a lot more than expected, but from what I have seen these patterns I am talking about are relatively consistent.
 
The spike I am referring to is the one that appears when you turn up the voltage, where there is a very sharp increase in temperature as you go over a certain voltage. From what I saw most SB chips don't have one that sharp, while IB chips all get it around 1.4V (If I remember correctly, it might be higher).

Heh, closer to 1.2v than it is 1.4v for Ivy.
 
Heh, closer to 1.2v than it is 1.4v for Ivy.

1.250 for 4.5ghz on mine 4.6 i couldnt get stable even at 1.325 but thats due to heat and using a stock intel cooler. i reccon if i has a dh14 or even h60/h80 i could probably get between 4.6 and 4.8 max on my chip but 4.5 is already more than enough but i didnt like the temps....

on topic
my neighbor has ordered this mobo along with a 3770k h100i and corsair 650 case with 2x 250gb ssds and a 2tb storage drive. i asked him if i could take some pics and he said nope lol but hopefully i manage to get a sneak at it so can truly comment on it :D
 
Back
Top