Optimus Foundation CPU Block - AMD

[Bavor]

All that said, we can typically find the culprit. Please send pis of your system so we can get some eyes on it.

I can't find the charger for my camera batteries, so I had to resort to cell phone pictures.

Here is the thermal paste spread on the CPU:

I forgot to take a picture of the CPU block before cleaning the old paste off of it, but it was an even spread of paste in the shape of the CPU.

Once I put the top radiator back in it was difficult to get a picture that showed the top mounting nuts. I tightened all 4 nuts in a crisscross pattern turning each one a few turns at a time the same way you would tighten the lug nuts on a car wheel that had 4 lug nuts.

Here is the system in the Define R6 case:

I removed one of the top radiator fans for the block removal and re-installation and to have a better view of the CPU block area for the photo.

Someone on another forum suggested that a single D5 pump is insufficient(too little head pressure) for the GPU blocks in parallel, the Optimus CPU block, and two radiators if you all up all the pressure drop. However I've seen 3 radiator setups run form a single D5 pump with the Intel Optimus block without issues. I'm not sure if there is a difference in pressure drop between the Intel and AMD Optimus CPU blocks.

I can bypass the GPU blocks and remove the GPUs then put in an air cooled GPU to see if there is a difference in CPU cooling performance.

 

[Caring1]

Perhaps you can explain the flow setup you have.
I would do pump > cpu > radiator > gpu > radiator > pump.
You appear to have pump > gpu > cpu > radiator > radiator > pump.

 

[Bavor]

Perhaps you can explain the flow setup you have.
I would do pump > cpu > radiator > gpu > radiator > pump.
You appear to have pump > gpu > cpu > radiator > radiator > pump.

I've read many places that it makes no significant difference based on testing of component order in the loop as long as you have sufficient radiator capacity and don't have a weak pump. I've also seen people who moved a radiator in loop order from after all the components to between the GPU and CPU and it made no difference in component temperatures before and after. The amount of time the coolant has in contact with either block is relatively short and the loop heats up and cools down as a whole. The pump is pushing about 4 liters per minute of coolant through the loop and the loop has a little over 1 liter in it. So its passing through the radiators a little less than 4 times per minute. Loop order only really matters if you run the pump at a low speed or you have a weak pump.

It seemed easier and also shorter run to go to the GPUs first. That's why I have the GPUs first.

Also, all the CPU temperature testing was done with the GPUs idle, so it wouldn't make a significant difference in CPU temperatures.

I tried taking out the GPUs and putting in the GT 1030 I have in their place. Then I reconnected the the tubing with the quick disconnect fittings I had before and after the GPUs.

I ran AIDA64 stress test, Prime95 small FFT, and Intel Burn Test on the Very High preset. The temperature differences were either 0C or 1C in the tests compared to running the same tests with the GPUs in the loop. It doesn't look like the D5 is insufficient in flow or head pressure if removing the GPU blocks make no significant difference.

 

[Bavor]

I think I found out why the Optimus AM4 CPU block didn't perform well. It seem that the Corsair XD5 pump doesn't perform similar to other D5 pumps.

I decided to build another water cooled PC using my old PC. I was going to use the corsair XD5 in that system and bought an EKWB D5 PWM pump for my current system. The EK pump and mount matched the all black theme better than the Corsair pump and mount.

When I swapped in the EK D5 pump into my current system and ran the same tests at both 3700 RPM and full pump speed, my CPU temperatures dropped by 6C in both AIDA 64 and the Intel Burn Test. My CPU temperature dropped 8C in Prime 95. It was obvious that the XD5 pump has much less head pressure or flow at the same RPM and at full speed when compared to the EK D5 pump.

EK D5 PWM pump specs state 1500l/min at 3.9m head pressure
Corsair for the same pump states 800l/min at 2.1m head pressure
https://www.corsair.com/us/en/Categ...eservoir-Combo/p/CX-9040002-WW#tab-tech-specs

I set the EK D5 pump to 1850 RPM and ran Prime95, AIDA64, and Intel Burn Test and recorded the temperature results. The results with the EK D5 pump at 1850 RPM were within 1C of the Corsair XD5 pump at 3700 RPM. So it looks like the Corsair D5 pump does have a much lower flow rate than the EK D5 pump.

I'm not sure why the Corsair D5 pump performs so much worse than the E5 D5 pump. I did see a YouTube video with a comparison of D5 pump/res combos and the Corsair XD5 did perform the worst of the pumps tested.

 

[Optimus Water Cooling]

Wow, that's some bad D5 performance there, 8c by swapping a pump is no joke. Congrats for figuring that out

 

[ThrashZone]

Hi,
Yeah I noticed the spec's difference long ago it's just not a D5
Some don't believe flow matters all that much but it really does it just depends on the chip being cooled how much it matters.

 

[Bavor]

Yeah I noticed the spec's difference long ago it's just not a D5

I think Corsair has a very poor pump top design.

Also Corsair and EK rate their D5's under different conditions.

Also, I don't know if my Corsair pump is defective or if the Corsair pump top design is really just that bad.

Some don't believe flow matters all that much but it really does it just depends on the chip being cooled how much it matters.

Flow matters more than people think it does. Especially with higher wattage CPUs and/or GPUs. Lower wattage systems can much more easily get away with poor flow.

Wow, that's some bad D5 performance there, 8c by swapping a pump is no joke. Congrats for figuring that out

I'm still trying to figure out why the Corsair pump performs so much worse. The pump makes no indications of being defective. It sounds the same as the EK D5 pump at the same RPM. I'll contact Corsair support to see if they have any ideas. The difference is huge.