Help with series v parallel graphics set ups needed


I’m relatively new to watercooling and want to learn more. I run two graphics cards in sli and don’t really understand the difference in setting them up in series or parallel. (I vaguely remember series v parallel from physics O level with electricity but that is a long, long time ago!). I think I understand what happens just not how the set up varies. My understanding is if you switch from series to parallel you halve the restriction from the graphics waterblocks but also halve the resulting flow through the blocks.

I initially had my cards set up in series I think. Water entered the top or first card then passed through a single sli connector tube to the bottom or second card then left via the second card. To facilitate tubing up my loop I switched to what I think is a parallel system. Water both enters and leaves via the top card and there are two sli connector tubes to the bottom card. There is no measurable temperature difference between the two set ups.

What I want to know is are there any variations which could help the layout of my loops in future. For example if I use a single sli connector but have the water both entering and leaving by the same card is that still a series set up ( or will it implode?). If I use two sli connectors with water entering through one card and leaving through another is that still a parallel set up? Clarification from someone more experienced than me would be appreciated.

I’ve got two other questions if anyone has time. Firstly I had a leak on one of my sli connectors and had to replace it. It was from Phobya and the connector tube is not locked but slides between the gpu fittings to accommodate different gaps. Does anyone manufacture a more secure arrangement which is not manufacturer specific (I know EK Waterlocks have a custom sli bridge for their CSQ range but it does not fit any other blocks). Secondly I want to buy some O rings for when I next change my loop and want to do some maintenance. The G1/4 rings are all 11.1mm diameter but there are two thicknesses available 1.6mm or 2mm. Does it matter which thickness I use? My barbs use recessed O rings if that is relevant. They are pretty cheap so I can buy a pack of each anyway but I just wondered if there was a definitive answer.

Thanks in advance for your help



A few months ago some of you helped me bleed my loop. I had a reservoir and Laing D5 Vario combination and was having trouble. What worked was turning the speed down to 2 on the Vario as someone suggested and running it for a few hours whilst occasionally switching the pump on and off.

Anyway I decided I didn’t want to go through that again so have replaced the combo with a separate dual bay reservoir and put an EK top on my pump. It now bleeds itself automatically in a few minutes and is quieter with higher pressure. It needed a bit of case modding to get everything in but was worth it.
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More about help series parallel graphics needed
  1. Well for my two video cards I went with a parallel loop system and it works great, but you may want to try a different way. This is what I came up with hope it helps
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