Non-restrictive SLI links?

[Scoob]

Hi all,

If there's one part of my water cooled build I'm least happy with it'd be the SLI links. I've used a pair of the Phobya telescopic ones, which looks great and were easy to fit but are much more restrictive than the rest of my tubing due to their narrow diameter.

I've used 1/2" ID tubing throughout, and I did use some slightly thinner tubing originally for my SLI links. I did this because my two GPU blocks did not quite line up, despite being from the same manufacturer. Since I had to replace one of my 570's I ended up getting a matching pair of blocks that lined up perfectly, so I got said metal SLI links.

Here's a link to the items I bought, it's to the site I bought from, I hope that's ok to link? Linky

I've had a search, but I cannot seem to find any similar SLI links that have a larger diameter, doesn't anyone know of any? I could (and actually still have from prior setup) use some wider tubing for the SLI links, but that's really fiddly, doesn't look as nice and I'd not trust the seal 100% Originally I used special stubby barbs between the GPU's (parallel flow) so I could easily fit the pipes in between, I then used cable ties to ensure things stayed in place. It worked very well, my GPU temps were slightly lower and much better balanced.

Basically, with my old manual setups both GPU's stayed the same temperature. With the metal SLI links the lower card can run 3-4c hotter due to the restriction. Not a big deal, but something I would like to address - call me a perfectionist if you will lol.

So, if anyone is aware of any metal, extendable SLI links that are nearer to 1/2" ID then I'd be very interested. The Phobyas are great, don't get me wrong, it's just due to the rest of my pipework they are restrictive.

Cheers,

Scoob.

 

[B NEGATIVE]

Bitspower Dplugs.

Tubing plays no real part in flow rates,the fitting bores are the determinating factor and they all shrink down to 8.5/9mm.
Flow is equal across the loop unless your cards are parallel flow instead of series.

 

[Scoob]

Hi B Negative.

Thanks for your reply.

I've looked at several of the D-Plugs and I've yet to find one that's long enough unfortunately.

I'd have thought tubing was fairly critical when it comes to flow rates potenially, depending on the rest of the loop. I DO use parallel flow and the Phobya SLI links are quite restictive vs. the prior barb & tube solution I was using before. The temperature difference and slightly higher temperatures overall than before confirm this.

I have made up some connections using my 1/2" ID tubing and a pair of compression fittings. However, this proved near impossible to fit as, even loose, the pipe is too firmly on the fitting, so turning each end opposite ways to screw into the GPU blocks was very tricky indeed. I might actually have to remove the GPU's, fit the tubing, and only then plug them in to the motherboard.

I may revert to my stubby barbs in the GPU Blocks with slightly narrower & more flexible tubing as before. Not a pretty, but it worked a lot better, and was a little easier to fit.

I will have to keep digging for larger ID solid SLI fittings, someone must do them.

Cheers,

Scoob.

 

[B NEGATIVE]

It doesnt make any real difference,0.5c being the usual gain.
Parallel flow is not something i recommend as water will find the path of least resistance,usually meaning a card will suffer as a result.
Parallel flow does increase overall flow but at the cost of reduced flow thru the card blocks.

 

[B NEGATIVE]

Read this http://www.specialtechforums.co.uk/showthread.php?1741-Graphic-Card-Parallel-v-Series

 

[Scoob]

The reason I asked about getting larger ID SLI links is because it HAS made a difference using a smaller diameter connection between the GPU blocks.

I could switch back to my original solution today, see my temperatures drop by several degrees and see both my GPU's no more than 1c different in temperature and usually exactly the same.

I had my prior build up and working in the summer and never saw a GPU go above 40c during gaming or benchmarking. Now, despite the much colder weather and lower ambient, I will often see mid-40's on the hotter card during benchmarking with the cooler card creeping into the 40's its self regularly.

So, the SLI links, while looking great, have made quite a difference to both the peak temperatures and the temperature difference between the cards.

This is no big deal in the scheme of things of course, it's just about achieving what I want. Much the same as those (like me) who prefer a more quiet build where possible, I love balanced temperatures on my GPU's.

I've already proven that fitting larger ID pipes between the GPU's "fixes" the problem, but would like to retain the nice solid metal SLI links, but a larger ID version.

Btw: that's a interesting post you link to, good reading. It's true of course that flowing through two cards in that way we'd expect to reduce overall flow. But, in my own testing and comparisions, it appeared that going through just ONE GPU block (when I removed one card) restricted the loop more than going through TWO blocks in parallel. This was confirmed as my CPU block is after the GPU's yet running just ONE GPU saw my CPU temps HIGHER, which confused the hell out of my at first.

With two GPU blocks back in play, even with the restrictive SLI links, my CPU temps improved again, though not quite to the same level as with the earlier, larger ID, tubing.

So, it seems from my testing, that a good Parallel flow setup for multiple GPU's can be very good for the overal health of the loop. My GPU blocks are obviously quite a restrictive part of the overall loop, other blocks may perform differently, but giving the water a second path to follow via parallel flow, appears to really help. I do have a very good pump - a D5 with High-flow top - so likely that helps too. Oh, I'm also going through a large Phobya 1080 rad, which I thought would be the more restrictive part personally, but that does not appear to be the case at all.

Again, this is all from my own personal testing and observation. I did a fair bit of reading on Parallel Flow prior to building my loop and I found it to be a very elegant solution, so wanted to pursue it myself & learn first hand. In the first version of my loop it performed better than I imagined. It's only since adding those SLI links that I get the imbalance & slightly higher temperatures that niggle me.

I do know that serial-flow works well too, and water cooling is all about the thermal capacity of the water and the first card "heating up" the second is a myth, as BOTH cards are way hotter than the water to start with, so can only benefit from it. This has been a fun learning project for me. By PC still worked & played stuff just as well when everything was air-cooled, I just find water cooling very satisfying and fun. To be honest the SILENCE is the biggest boon, as air-cooled SLI was...intrusive to say the least!

This is interesting stuff!

Scoob.

 

[B NEGATIVE]

All of what you say could be a bad mount on your new block or the new card is churning out more heat,it doesnt mean that the pipe ID is causing this.
Restriction doesnt cause a 4-5c jump,0.5c is more like it.

All your testing has proved is that your cards are not getting flow,if one card is causing restriction greater than 2 then parallel flow is not feeding the cards correctly,the CPU gets better temps as the water isnt being used to its fullest in the GPU blocks.

 

[Scoob]

Hi,

Good points, however this does not quite match my testing. I've not been perfectly clear and given the full details of each and every step I've taken for fear of creating confusion. Looks like I've managed that regardless lol.

To be clear, the GPU's and Blocks I have now, perform better if I replace my current adjustable telescopic Phobya SLI Links with the older "barb + pipe" custom links I used previously. However, with this setup, I need to cable tie the pipes to ensure a good tight fit. This is in part due to the fact that I have special shortend barbs to enable much easier manipulation of the pipe, resulting in a less secure fitting. Remember, these were first used when the GPU blocks were offset slightly, so the flexibility was crucial.

Now, as I don't entirely trust the barb + pipe approach not to leak, I made a similar connector using my good Phobya compression fittings and some of the 1/2" ID pipe I used for the rest of my loop - so, even less restrictive in theory. However, these proved so tricky to fit that I gave up and stuck with my metal Phobya SLI links.

So, the thin hose and barbs of the original links I made, work better with this setup than the metal Phobya SLI links, but I worry about them leaking. The new 1/2" ID pipes I set up should work better still, but were a little too fiddly to fit so I gave up - though I might revist this. They also don't look anywhere near as nice, which is a consideration too. The perfect solution I thought, was simply to get a larger (ideally 1/2" ID) version of the metal telescopic SLI links. That way they would look good, be easy to fit and I'd trust them not to leak.

Note: both my GPU's are GTX 570 Revision 2's, so both have the EK SE rev 1.1 block so should be equally restrictive or not in their own right. It just seems to be the SLI link ID that makes a difference.

Sorry for not being clear, hopefully my original question regarding some larger SLI links makes more sense now.

Scoob.