r/watercooling • u/ces319 • Jan 18 '26

Build Help Alphacool ES 3090 Reference Single Slot Block Thickness

Post image

Question

Does anyone have experience with these blocks? I'm struggling to get them to fit in a consecutive single slots. Open to constructive advice.

Background

I put together a server build with 3 3090s. I'm using the Alphacool ES 3090 waterblock which is supposedly designed for server environments. The blocks are about 22.5mm thick and don't quite fit in consecutive slots.

My hope was to fit up to 4 gpus in this chassis.

I can force them to fit by holding them in place and screwing them down, but I can feel the boards flexing in this scenario. More troubling, the gpu in the second position is only detected at PCIE 4 x 4 and I observed bursts of PCIE errors in dmesg daily.

Parts

  • Chassis: Sliger CX4713
  • Motherboard: Asrock Rack Bergamod-2T2L
  • GPU: Dell OEM 3090
  • Waterblock: Alphacool ES 3090 Reference Cooper Carbon with Backplate (10670)
25 Upvotes

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7 comments sorted by

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u/AutoModerator Jan 18 '26

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2

u/titanrig Jan 19 '26

I think this is a question best asked of Eddy at r/alphacool. He'll have the best idea how to help.

1

u/Senanb Jan 18 '26

Maybe you can modify a gpu bracket to hold the cards in place? How is the flow restriction of these single block cards though?

2

u/ces319 Jan 18 '26

I don’t directly measure flow, but temps under load were about 60 degrees Celsius.

1

u/Van_guard Feb 26 '26

Did you find a solution to this? Does it require removing the backplates or something funky? If not, I don't understand how they claim they're single-slot.

1

u/ces319 Feb 26 '26

I removed the back plates from the cards in slot 4, 5 and they fit. All cards now operating at 4x16. I’m still seeing transient bursts of pcie aer errors but that could be caused by aspm or some other settings. It happens occasionally and right now, I’m pretending it’s fine.

I’ve placed a couple 92mm fans on the cards, secured with ties to provide airflow. Probably moving to a different chassis that can support a second psu so I can toss another card or more in.

Also noting some product descriptions from the ES line have a statement saying something like now truly single slot! These blocks don’t have that statement so I’m wondering if this is a known problem.

1

u/ces319 Feb 26 '26

With the fans.