The Neophyte's Custom Liquid Cooling Guide: How To, Why To, What To Expect
by Dustin Sklavos on September 30, 2013 12:01 AM ESTThe last part of our objective testing is in measuring noise levels, thermals, and power consumption. All of these theoretically go up due to increased voltages on the CPU and graphics cards as well as just the overhead in running the liquid cooling system. Remember that we've added a water pump and essentially increased the number of case fans from three to six.
As I mentioned in my initial review of the Corsair Carbide Air 540, noise levels for the case itself aren't particularly stellar but they're not horrible either. Where we do benefit from the Gigabyte G1.Sniper 5 motherboard is its spacing between the two graphics cards; the board is designed to support four cards, so there's plenty of room for both cards to breathe.
First, we'll take a look at thermals.
What should be striking is the increase in temperatures on the CPU going from air to water, but remember that we also were able to add a substantial amount of voltage in the process to hit 4.4GHz. Doubly striking is the way the load temperatures on the 780s are more than halved.
Despite the GPUs drawing substantially more power (and thus generating more heat) than the CPU, they also have much higher surface area and less overall heat density. We also benefit from direct contact between the heatsink and the GPU die, while Intel uses poor quality glue and thermal paste to bond the 4770K's die to the heatspreader. Ultimately it becomes too difficult to transfer heat off of the 4770K fast enough.
The reality is that none of these noise results are particularly uplifting, but there is a silver lining. If you shift down to 4.3GHz and lose all that voltage that was needed to hit 4.4GHz, you can also reduce the speeds on all of the fans and at least get your noise levels down substantially. Idle noise drops to about 31dB, with load noise closer to 35db or 36db. It's a lot more tolerable.
Given the way idle voltages are handled by Haswell and Kepler, it's reasonable to suggest the liquid cooling system adds about 15-20W of overhead as opposed to air cooling. Subtract 20W for the loop, and you're looking at our modest overclock tacking another 30W of power consumption on over the air cooling system. I'm at least a little nervous about what will happen when I flash the BIOSes of the GTX 780s to unlock a small voltage boost down the road.
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hot120 - Monday, September 30, 2013 - link
Awesome article!blanarahul - Monday, September 30, 2013 - link
Hmm.. Can you try cooling those 780s alone? Overclocking the CPU seems pointless on Haswell.valkyrie743 - Monday, September 30, 2013 - link
overclocking haswell is not pointless. just is a pain (same with ivy bridge) cause intel decided to be cheap and not solder the IHS to the cpu. if you do a mild overclock its fine give or take how bad the tim on the cpu/ihs is. but if you plan on doing high overclocks and water cooling like this. you might as well de-lid the cpu and apply your own tim. temps on air (if done right) drop a good 15 to 20C under load. I've seen people hitting 90 C and go down to 70 or less underload. and thats on air.the reason why i have no upgraded from my sandy bridge 2600K. @4.5ghz right now at 1.28 volts and my max temp running intel burn test was 70C (air)
The Von Matrices - Monday, September 30, 2013 - link
Please read my post in response to NeatOman. The result is correct but the reasoning is incorrect.gandergray - Tuesday, October 1, 2013 - link
For information about removing the cpu lid or integrated heat spreader, see the work performed by Idontcare: http://forums.anandtech.com/showthread.php?t=22618... .iTzSnypah - Monday, September 30, 2013 - link
You are cooling way too much with only 600mm worth of radiators and your deltaT is obscene. Take out 1x GTX780 and retest if possible.NeatOman - Monday, September 30, 2013 - link
I think the thermal paste between the cpu and the lid are the limiting factor here, i believe that not only will 4770K do better with better thermal paste in between the lid and cpu on just air cooling alone but also might have a larger difference between the air and water cooling.And of course there is also a full delid which i think wont be much of a threat because with water cooling you don't need the motherboard to support a large heavy cooler.
NeatOman - Monday, September 30, 2013 - link
Sorry, i meant that you wont need to put a lot of pressure like if you where supporting a large air cooler with the motherboard.The Von Matrices - Monday, September 30, 2013 - link
The issue is not the composition of the thermal paste between the die and the lid; it is the thickness of the thermal paste between the die and the lid. It's widely reported that in Ivy Bridge and Haswell there is way too much of a gap between the die and the lid due to the thickness of the glue used to secure the lid to the package. You can solve this by removing the lid, using a razor blade to remove all the glue, then put on new TIM and place the lid back on the package. No matter what new TIM you use you will get drastically reduced temperatures.Either way, Haswell runs hot due to its FIVR, and there's nothing that can be done through beefier heatsinks, delidding, or changing thermal paste that will make it cooler than an equivalently modified Ivy Bridge.
dragosmp - Monday, September 30, 2013 - link
Still, it is incomplete. The thermal transfer formula is simply Rth=rho*L/S, more thermal resistance (Rth) more the temperature delta is high between the source and ambient: deltaT=Power*RthAsuming the power is constant, to decrease deltaT you need to decrease the thermal resistance, so:
*S is the die surface, can't change that
*L is the thickness of paste - you're right, it needs to be as thin as possible; put 2x too much and you have twice the deltaT
*rho - thermal resistivity (1/lambda) - it depends on the material; Intel does use cheap paste with a conductivity around 3; were they to use fluxless solder or at least some AS5 they'd decrease the thermal resitance by a factor of 2 easily, thus offsetting a thicker than needed layer of paste.
My 2 cents: for performance the paste must be removed and replaced with something better plus as you say remove the glue to reduce the thickness. Of course one should be careful not to chip the die, but these two things really help.