Originally Posted by PepeLapiu
You are picking at straws.
Imagine you tie your fans to your CPU temps.
1) Your fans won't speed up if it's only your GPU getting hot. And I have NEVER heard of anyone before you who gets his CPU to work harder than his GPU during gaming.
2) Your CPU gets hot but your water temps will not warm up right away so your fans get turned.up too soon, and they will also get turned down too soon, causing a less smooth speed curve.
And #1 also applies in reverse if you tie your fans to your GPU temps. When doing a CPU intensive task, your GPU will be idle and slow down your fans.
No, not picking at straws. Your logic is sound .... your justifications and reasoning however are based upon false assumptions and misstatements. I have 6 temperature sensors and monitor water temps at 4 points and air temps at 2 points in real time. You have made an incorrect assumption that the CPU is lightly loaded and at a low temp during gaming and this simply is not the case. I am not objecting to your reasoning for controlling fans via water temps, but the supporting statements I take issue with are:
1. "But your CPU is idle when gaming".
No, your CPU is by no means idle when gaming, and especially multi-player gaming. I have constant view of all my individual core temps and GPU temps and have never seen the situation you have described. I'm looking at the Logitech LCD panel which displays this information as I type and CPU cores are in mid 20s .... when gaming it's typically at 55-65C, facts conformed by looking at Afterburner and HW Monitor recorded maximum temps when the session concludes.
Can we agree that CPU cooling is far more prevalent than GPU cooling ?....the very existence of the AIO industry I would think conclusively settles this question in and of itself. Overclockers are primarily gamers so why are all these gamers foregoing GPU cooling and plopping on H100i's if they have idle CPUs while gaming ? Improving gaming performance is the whole idea of CPU overclocking.
2. "CPU goes for a cool nap and tells your controller to slow down the fans when you need them to speed up for your GPU." is not correct
This does not actually happen. As in the example above the CPU temps when gaming are as much as 15-25C HOTTER
than the GPU ... so these much hotter temps can certainly not be considered taking a "cool nap" and nothing would telling anything to slow down the fans. I just ran Furmark .... a worse case scenario for low CPU loads w/ high GPU loads ...... and the Core Temps were ~ 55C whereas the GPU never broke 44C ...rad fans never broke above the minimum fan speed I set of 450 rpm....after watching the test, decided to go to 550 rpm
3. "With PWM, you can't control your fans based on water temps."
No true, at least not without contextual boundaries...... You are assuming that any input from the MoBo is via PWM, it is not. If I didn't use PWM feed from the CPU headers but instead I used the VCC MoBo CHA headers, would all be "hunky dory" ? The way in which you have stated your case, no differentiation is made via inputs or outputs. PWM Output from a fan controller can certainly be used to control PWM fan speeds based upon an input from a thermal sensor. If you took your controller and designed it so it was capable of output to PWM fans, how would the function of the unit change in any way ? The Aquaero will for example control PWM fans and IIRC the 5 had like 12 point programmable curves for temp sensors (not sure of the 6).
a) PWM inputs from the MoBo can not be used control your fans based on water temps .... unless of course the MoBo has input sensors and a PWM output associated therewith. Not aware of any MoBos actually so equipped but the fact that most of the high end stuff now comes with 10 or so 4 pin fan headers implies this will be something we'll see in the near future.
b) PWM outputs from the Fan Controller can be used control your PWM fans based on water temps as in the Aquaero
Not that a) could not be done....The Asus M6F for example includes 3 temp sensors that plug into the MoBo..... it also has three 4 pin (not PWM) fan headers associated with these inputs and provides BIOS control of these fans. FanXpert2 however does not as yet control these fans. Hopefully FanXpert3 will .
VVC and PWM are simply two ways of controlling fan speeds..... it by no means restricts or limits what inputs are used to determine what speeds. As I understand your position, it's about what you are measuring to serve as the basis for fan control, not whether the speed of the fan is slowed down by longer periods between voltage pulses or voltage reduction. PWM or VCC control are on the output side / temperature monitoring or MoBo headers are on the input side and these can be either VCC or PWM.....
4. "I have NEVER heard of anyone before you who gets his CPU to work harder than his GPU during gaming"
I wasn't aware that anyone made such a statement. But I thought we were talking about how hot the GPUs and CPUs are getting not how hard something is working. A GPU at 110% of TDP, due to the relative sizes of GPU and CPU waterblocks will not get anywhere near as hot as the CPU even at much lower loadings
5. When running a CPU ONLY intensive task and no GPU load, fan speed is a non issue. Let's use a typical CPU / GPU cooled system with 2 cards at 300 watts draw and a 140 watt CPU ... Basically, with the GPUs doing nothing, you have just 1/5th the load you designed your system for (140 / 740 = 19%). At such a miniscule loading, minimum speed on those fans will be more than enough for any CPU ONLY task ....
I just ran Prime95 and my water temps are 25.9 with an ambient of 20.9 .... a Delta T of just 5C w/ CPU temps in the high 60s. Pushing the speed to 1200 rpm max for 10 minutes and I am able to get this down a whopping 0.5C to 25.4. Turning them off completely, and 10 minutes later, I realized a water temp of 29.8 .... not exactly a Delta T there of great concern there at just 8.9C .
6. "Your fans won't speed up if it's only your GPU getting hot."
Well first, no such condition has as yet been encountered and second, 2nd, when does a water cooled GPU ever get hot before the CPU does ? No matter what I do I can NOT make my GPUs get hot. When using CPU based fan control, I can't get the GPUs over 44C.....Peeps don't really need to ramp up fan control to protect the GPU because at any CPU loading the amount of cooling be applied is more than adequate. I have Furmark running now with 100% TDP (Core hovering around 1089) and fans at a fixed rpm of 550
4 minutes in, I'm at 38C GPU temp w/ a coolant temp of 31.6C
8 minutes in, I'm at 44C GPU temp w/ a coolant temp of 34.6C
12 minutes in, I'm at 46C GPU temp w/ a coolant temp of 37.0C
16 minutes in, I'm at 48C GPU temp w/ a coolant temp of 38.7C
20 minutes in, I'm at 48C GPU temp w/ a coolant temp of 39.0C
Here's 110% TDP (25% OC on GPU and 20% on memory) at 850 rpm .... didn't allow system to cool down before starting so began at 36C
Oops, missed 4 minute reading
8 minutes in, I'm at 44C GPU temp w/ a coolant temp of 33.9C
12 minutes in, I'm at 44C GPU temp w/ a coolant temp of 34.4C
16 minutes in, I'm at 44C GPU temp w/ a coolant temp of 35.1C
20 minutes in, I'm at 45C GPU temp w/ a coolant temp of 35.3C
Here's 110% TDP (25% OC on GPU and 20% on memory) at 1200 rpm .... didn't allow system to cool down before starting so began at 37C .
4 minutes in, I'm at 41C GPU temp w/ a coolant temp of 31.3C
8 minutes in, I'm at 41C GPU temp w/ a coolant temp of 31.9C
12 minutes in, I'm at 42C GPU temp w/ a coolant temp of 32.0C
Equilibrium reached, test suspended
So what can we conclude from these test results ? .... BTW pump speed was locked at about 2000 rpm thru the whole testing. Simply put, using fan control, we were able to effect a difference of a mere 3C on the GPUs in the audible fan range down to the minimum speed ..... big deal ? Not at all
Your logic is sound and the conclusions drawn are very well thought out.... logically and theoretically pretty much everything is spot on (except for the PWM thing) .... the plain fact is however the assumptions you started with are not "real world". I won't argue that using water temps to control fan speeds is not the best of all worlds....however....
1. You can do that using PWM fans and a PWM controller using temp sensors as inputs.
2. CPU tasks exists (i.e Prime 95) which do not significantly load GPUs but it's irrelevant in that even at minimum fan speeds a system designed for 2 heavyweight GFX cards and an CPU both OC'd will have no trouble handling 100% CPU load at minimum fan speeds.
3. GPU tasks exist (i.e Furmark) that will put maximum loads on GPUs and minimal on CPU but all fan speed control does is deliver a mere 3C temperature difference in the audible fan range. On top of that the highest GPU temp at minimum fan speed is more than 30C below a temp that anyone need be concerned about and 15-25C less than the CPU temps seen while gaming. In short speed control for water cooled GPUs brings nothing to the table.
4. Since games do use the CPU and GPU, while not exactly following each other and varying from game to game.... each of them kinda goes up for the most part with each other and in the end.... differences are there but they really ain't that big.