A great discussion! I thought I’d add to it and hopefully clarify some points:
The testing regime I’m undertaking is to enable an apples-to-apples comparison among waterblocks. The concept is to control inlet temp, waterflow, heat load and mounting pressure, so that the only variable is the waterblock’s performance at these parameters.
If I were to introduce another variable by letting waterflow vary among the blocks, then I think the comparison is then compromised – I can see a chorus of voices saying “But block x is at 1 gpm and block y is at 0.5 gpm – unfair!”
The point was raised that this may make unfair comparisons between high and low pressure drop blocks. I think users must make a determination if, in using commonly available waterpumps, it is better to go for a high pressure waterblock at a lower C/W or one with low pressure at a higher C/W and bank on increased performance due to higher waterflow through it.
Bear with me as I present some data:
I interpolated data from Bill A’s summary charts as follows:
Data from Bill A’s Tests
Delta C/W
<1 gpm >1 gpm
Tsu 4.5 2.5
WW 3 C 2 C
Slit 3 1.5
SW 1.5 0.5
WW = Whitewater, Tsu = Tsunami, Slit = BeCooling Slit Edge, SW = Swiftech 5002.
The deltas represent the difference between data points at the low and high ends of the curves.
A VERY clear message – the performance risk with waterblocks is under-performance at the low end, and more so with high pressure waterblocks. In absolute terms, the “high flow” advantage may be about 2C, while the “low flow” risk is more like 2-5 C.
***NOTE: I excised comments about radiators and flow per Cathar's comment below.***
As to displaying data, I again interpolated data from Bill A’s tests:
C/W @ 1 gpm vs Head Loss
WW 0.18 @ 1.05 mH2O
SW 0.21 @ 0.48
Slit 0.22 @ 0.3
Tsu 0.24 @ 1.85
If you imagine a graph of the data, you will see a graph similar to the approach I’m using currently. There is a general conclusion that Whitewater is the block to beat, but a simple rank of C/Ws at 1 gpm could be misleading without noting pressure drop.
OK – let’s keep pressure drop constant and let flow rates “float”:
C/W @ 0.5 mH20
WW 0.190 @ 1.0+ gpm flowrate
SW 0.210 @ 1.5+
Slit 0.215 @ 1.9
Tsu 0.262 @ 0.7
Same relative ranking, although positions could conceivably change. Note the obvious correlation to pressure drops.
We both felt that a good representation of performance would on the basis of C/W @ 1gpm, noting pressure drop, as it is an important piece of data that should be included (for reasons which now should be obvious). Users must take note of the “cost” of performance due to pressure drops, specifically as to waterpump selection.
Some concern has been expressed about using a different waterpump and its impact on results. I will argue that there is no difference due to the pump used. The reason is that 1 gpm through the test rig will yield the same waterblock psid regardless of how 1 gpm is generated – it could be from a pump x, y, or from a 100 gallon tank of water suspended 15 feet over the test rig using a gravity feed. I changed to the more powerful pump so that I could get to 1 gpm for some very high pressure drop waterblocks.
For each waterblock, psid @ 1 gpm is independent of the pump used. If this assumption is incorrect, don’t hesitate to point out the why and how.
It would then seem that I’m arguing for presenting more data, at different flow rates, than I’m currently showing.
I think I might be able to do this without undertaking a week’s worth of testing – right now, each block takes about two days to test. I am not getting paid directly for this work, and even if I did, I can’t afford a week per block.
This is a bit of a ramble and quite long, but I want to present data the best possible way within constraints I have to live with, so your opinions are of great value to me. I am on the road, so bear with my response time. Let the discussion fly!
Joe
PS: I hope my interpolations are OK!
The testing regime I’m undertaking is to enable an apples-to-apples comparison among waterblocks. The concept is to control inlet temp, waterflow, heat load and mounting pressure, so that the only variable is the waterblock’s performance at these parameters.
If I were to introduce another variable by letting waterflow vary among the blocks, then I think the comparison is then compromised – I can see a chorus of voices saying “But block x is at 1 gpm and block y is at 0.5 gpm – unfair!”
The point was raised that this may make unfair comparisons between high and low pressure drop blocks. I think users must make a determination if, in using commonly available waterpumps, it is better to go for a high pressure waterblock at a lower C/W or one with low pressure at a higher C/W and bank on increased performance due to higher waterflow through it.
Bear with me as I present some data:
I interpolated data from Bill A’s summary charts as follows:
Data from Bill A’s Tests
Delta C/W
<1 gpm >1 gpm
Tsu 4.5 2.5
WW 3 C 2 C
Slit 3 1.5
SW 1.5 0.5
WW = Whitewater, Tsu = Tsunami, Slit = BeCooling Slit Edge, SW = Swiftech 5002.
The deltas represent the difference between data points at the low and high ends of the curves.
A VERY clear message – the performance risk with waterblocks is under-performance at the low end, and more so with high pressure waterblocks. In absolute terms, the “high flow” advantage may be about 2C, while the “low flow” risk is more like 2-5 C.
***NOTE: I excised comments about radiators and flow per Cathar's comment below.***
As to displaying data, I again interpolated data from Bill A’s tests:
C/W @ 1 gpm vs Head Loss
WW 0.18 @ 1.05 mH2O
SW 0.21 @ 0.48
Slit 0.22 @ 0.3
Tsu 0.24 @ 1.85
If you imagine a graph of the data, you will see a graph similar to the approach I’m using currently. There is a general conclusion that Whitewater is the block to beat, but a simple rank of C/Ws at 1 gpm could be misleading without noting pressure drop.
OK – let’s keep pressure drop constant and let flow rates “float”:
C/W @ 0.5 mH20
WW 0.190 @ 1.0+ gpm flowrate
SW 0.210 @ 1.5+
Slit 0.215 @ 1.9
Tsu 0.262 @ 0.7
Same relative ranking, although positions could conceivably change. Note the obvious correlation to pressure drops.
We both felt that a good representation of performance would on the basis of C/W @ 1gpm, noting pressure drop, as it is an important piece of data that should be included (for reasons which now should be obvious). Users must take note of the “cost” of performance due to pressure drops, specifically as to waterpump selection.
Some concern has been expressed about using a different waterpump and its impact on results. I will argue that there is no difference due to the pump used. The reason is that 1 gpm through the test rig will yield the same waterblock psid regardless of how 1 gpm is generated – it could be from a pump x, y, or from a 100 gallon tank of water suspended 15 feet over the test rig using a gravity feed. I changed to the more powerful pump so that I could get to 1 gpm for some very high pressure drop waterblocks.
For each waterblock, psid @ 1 gpm is independent of the pump used. If this assumption is incorrect, don’t hesitate to point out the why and how.
It would then seem that I’m arguing for presenting more data, at different flow rates, than I’m currently showing.
I think I might be able to do this without undertaking a week’s worth of testing – right now, each block takes about two days to test. I am not getting paid directly for this work, and even if I did, I can’t afford a week per block.
This is a bit of a ramble and quite long, but I want to present data the best possible way within constraints I have to live with, so your opinions are of great value to me. I am on the road, so bear with my response time. Let the discussion fly!
Joe
PS: I hope my interpolations are OK!