Date: Tuesday , February 19, 2019
As noted above, Alphacool sent over three of its new GPU water blocks, these built specifically for NVIDIA RTX 2080 Ti cards. We have the Eisblock GPX Plexi, GPX Acetal, and GPX Plexi Light. All three of these GPU blocks share the same common water block structure, but are dressed up in different ways as the video below will show you.
We did run into some issues with our initial installation tests with the GPX Plexi and GPX Plexi Light. We tried fitting both blocks, and both showed the same issue. We did this to ensure that we did not have a faulty block. The two different models have slightly different mounting procedures as well, so we wanted to see if that was coming into to play also.
As you can see below, a "curvy" PCB on your $1200 video card is not a good sign of everything fitting properly.
We always test fit our water blocks, be it on GPUs or CPUs. Pulling the block off, this is what we found.
Certainly that is not the kind of mate you want to see on your GPU. It is quite obvious from the pictures that the GPU is not making proper contact with the coldplate. Of course we would like to see a nice rectangular footprint with most of the TIM flowed out to the edges of the GPU. It is worth noting that this is also our second test fitting on our our second Eisblock. In the pictures above, we even applied an "extra" dab of TIM in order to help judge just how much spacing we had above our GPU. Our two prior tests showed even worse mating results.
Once both of our blocks showed the exact same issue, my first thought on this was that the wrong thermal pads were supplied with the kit that we got from Alphacool. I have been supplied the incorrect thermal pads in the past so my mind immediately went there. 1.5mm pads are specified in Alphacool's literature and our pads measured out at 1.46mm thick, so the pads were in specification, but the pads still seemed to be the problem. Either that or we had two GPU blocks that were not in spec.
I reached out the Alphacool and supplied pictures and explanation of our procedures and they were quick to respond, that we indeed did have a thermal pad issue. However, it was not that our supplied pads were out of spec, but rather that the card we were installing the coolers on had a large variation in VRAM Z-height.
The RTX 2080 Ti FE card we are using is the second RMA card that we got back from NVIDIA after our second failure. It is equipped with Samsung VRAMs, and not the Micron memory that was seen on many early cards, and Micron is likely the VRAM that was on the cards when Alphacool designed their blocks. I am surely theorizing here, but it seems to make a good bit of sense that a change in VRAM manufacturers could surely give us a bigger swing in tolerance when it comes to Z-height.
Alphacool did have this to say about VRAM Z-height.
The issue is, that the v-rams have sometimes different sizes. The height is sometimes different. We are talking about 0.1mm, 0.2mm, up to 0.3mm. And our manufacturing tolerance are around 0,1 mm. So, in some rare cases, if everything is going wrong, the different oft he height could be up to 0,4 mm. That is the worst case szenario. And it seems like you got the worst case szenario.
So it looks like we will have to use some thermal pads with a 1.0mm thickness to get the proper mate between our coldplate and GPU. Alphacool did offer to send a new kit from Germany, but we elected to source those locally as it would simply be more efficient. We did find these on Amazon with an extremely high thermal conductivity rating and those should be here today.
Surely we will be doing a follow-up to let you know how all this works out. However we thought this made a good article for those of you wanting to do some custom loop water cooling in that everyone should always do a test fitting to make sure you are getting good mating surfaces with all your components, especially that tremendously expensive GPU.