I'm out of the loop for watercooling...

It has been quite a while since I did water cooling, not counting the AIO units I've used on two CPUs within the last year. Thanks in part to the TimeSpy thread, I'm finding an urge to have a go at competitive benchmarking. Not helped I also recently got a 3DMark licence in the earlier Steam sales so running those got a lot easier.

Not wanting to spend a huge amount on this, I think my best option is to water cool my 980Ti. Right now it thermally throttles even under normal gaming loads at stock, so I've not got the full value out of it. I'm not going SLI Titans or anything like that, and the 980Ti still seems to have more potential than the 1070 I got recently, providing I can get the clocks up.

I suppose I have two options here. The easy option is to get something like a Corsair 280mm AIO and their adapter kit to fit it on the GPU. My GPU is a reference blower model so is compatible with that. This is pretty low cost and easy to do.

The other option is to think about going full custom. I need to double check what rads my case supports, but I think a 280 is safe. I'd need to research blocks, reservoirs, pumps... and at what cost. Would it perform that much better over an AIO of same rad size? And if I go full custom, I might be tempted to take the AIO off the CPU and add that to the loop too...

After looking again that the Corsair solution, I'm reminded why I didn't go for it previously. There's a rather scary thread on their forums with various problems.

The other option, a more serious loop, is looking rather expensive. How is EK kit regarded? A GPU block on its own costs almost as much as a bigger Corsair AIO (without GPU mount adapter), and to get the rest of the kit is not insignificant. If I'm going to do this, it will have to be a serious "once done, don't touch again" job and I will essentially freeze my system spec, which makes me wonder if I should drop a 1080 in there first.

Why can't I find hobbies which don't involve spending lots of cash in some way?... the worrying part is, I can afford it, if I choose to...

From what I've read the EKWB Predator kits have reviewed quite well. If you only plan to cool the GPU it should be OK to remove the CPU from the loop and add a GPU to it instead, if you plan to do both you will almost certainly need more rad.

I was looking at their kits https://www.ekwb.com/solutions/kits/ which I saw on a random look at one of my preferred suppliers. I have no idea how much rad I need, as opposed to what I can fit. If I keep my CPU on the existing Corsair AIO, my existing case has room for either a 280 or 360 for the GPU.

I just had a flashback to a Fury X I had for a short time. I felt it could use a lot more rad even at stock... note: what I consider adequate is usually very different to what marketing departments considers adequate.

Don't forget the XSPC D5 kits. Those are nice expandable custom pre-kits.

If you're looking for a maintenance free setup, stay with AIO and use the GPU brackets as you said earlier. If not, you can purchase this CPU only kit and just add more affordable GPU universal block and add more raddage.

You list a GTX 980 ti of which there are many brands and changes past the reference design so you'll need a full coverage water block to fit your exact card and you're looking at spending no less than $100 on that part of the cooling loop alone.

The kit you choose radiator wise has to be able to fit in your case so research into what size radiators you can actually put into it.

The EK kits are a good choice and so are the D5 XSPC kits that Jack mentions.

Going from air cooling your GPU to full coverage water cooling is going to yield better load temperatures even with a simple 120 radiator but the larger the radiator cooling field the lower your GPU load temperatures will be.

Nothing is pushing you right now so you have plenty of time to research all your options.

You can always use an universal GPU block. They are cheap, you can swap between the 980 ti and the 1070 (or whatever card yuhave around ) and unless you go crazy on voltage, a fan blowing on the VRM's/RAM chips is enough.

To recap where I am now...

My case is a Corsair Air 540, so plenty of room inside. The top 280 mount is taken with the CPU AIO, which still leaves me the front to fit either another 280 or 360. I plan to leave the GPU AIO system untouched and separate from the GPU loop. In terms of area 3x120^2 > 2x140^2 but I don't know what the useful effective cooling area between them is. The price difference between them is not significant.

GPU and block wise, as said I have a reference 980Ti so I hope it would be easy to find a block for that. Looking through EK's list, they seem to do one for a lot of the major after market cards also.

I'm still leaning towards EK due to local availability and looks but haven't made any decision.

Mackerel, Sounds like you have alot of options. I'm sure your aware both Aio and custom loops would both yield better cooling results than your stock blower, though I'm sure it could benefit from a better thermal compound. The Aio will probably cost the least. However if you are wanting to benchmark competitively I would definitely suggest a custom loop. You can Google cooling results for all the custom GPU blocks you are considering. The more restrictive blocks are more efficient at lower pump speeds, but may need higher pressure. The higher fin count rads are also more efficient at moving heat but require higher pressure fans or higher speeds. Being you are keeping both loops separate, personally I would choose a block which is more efficient at lower pump speeds while using lower fpi rads with high cfm fans to keep the noise down. But it's down to what you want. That being said I would choose a tubing with the largest ID you can fit with the right fittings for your loop components. Just need to make sure the lines can supply all components without limiting volume.

I should have also added, with the case setup you mention. Your CPU Aio is in the top and you want the rad for the GPU in the front. I also think it would be best to use the largest you can fit or afford. With the logic that it will be heating your intake air for the rest of your system. Therefore use lower fpi rad so as to keep from limiting intake air and the largest you can get to spread the heat over a larger area, rather than having a concentrated blast of heat entering your case.

I was planning to run fans on both rads as exhausts. This does mean I'll have to reverse the rear fan (currently also exhaust) or just not bother at all. There are enough vents around the case that I don't think it would restrict airflow through the rads. The only downside is the case might suck up dust, but even with filtered intakes it has found its way in already.

Well to be honest I don't think I would run them both in exhaust. But that's gonna depent on your specific case. If there are enough vents then that's probably specific to your case. I think if you wanna try that then you should just experiment to see how you get your best or desired results. If it were me, I would first try Aio, exhaust. Rear fan exhaust. Front rad intake. With that type of setup you will reduce turbulence and dead air spaces. Front to back, bottom to top. Heat rises, coolest air comes in from the lowest point possible. Just going off of temp logic. I apologize if that sounded condescending. But as mentioned it never hurts to experiment. Move things around and experiment with intake, exhaust, push,and pull setups. If we all did the same thing how would we progress? But one thing I have noticed. Most Aio setups tend to be push, probably for ease of mounting or something. All rads are more efficient and quiet with the fans pulling if you eliminate all other variables.

I could move my AIO rad to the front, and put the GPU rad up top, but that means I have to go 280 and not 360. Rough estimate the 360 should have about 10% more potential area than a 280, all else being equal. I'd really want the GPU rad to exhaust since that will be the bigger heat source. I did try running the CPU rad intake before reversing it later, and it didn't make any significant difference.

Does fan pulling really make a difference over pushing? I thought I had looked before and there didn't seem to be any significant difference. I went push on mine as that meant I could see the LED fans. They did develop a vibration problem over time and I've only recently replaced them with Noctua ones which totally don't fit with the colour scheme in the case, but I'd rather not have the vibration... if I move them the other side of the rad I wont see them any more... tempting...

I didn't suggest that but that is exactly what I intend to do with an upcoming system. CPU front, GPU top. Using the exact same thought process. CPU is cooler. In your case, the only issue being you would then be limited with radiator size. But being it will be on its own loop, a 240 should still suit you just fine. As for push pull, it should show up at extremes, or be more efficient at lower fan speeds. The reason being surface area. You use more surface area of the rad in a pull setup. Much like a velocity stack in automotive terms. Not to mention the noise benefit. Vibration is definitely something that wouldn't be tolerable for long. Should be interesting to see what you come up with in terms of temps and configuration with your final setup. 240 are cheaper than 360 and should still be plenty. Your power supply will probably be happier pushing fewer fans too.

I'm thinking 280s, not 240s, if I want the flexibility of mounting it on top. The EK 280 kits are slightly cheaper than 360 kits, but not in any useful way. I don't think I'm short on power. Got a 750W and the current system as it is, when running prime95 + furmark is only around 400-ish W.

Well you've got plenty of power, so that won't be an issue. I was just thinking in terms of total wattage. But my mistake on rad sizes. Hey 280 is definitely nicer than 240. So that's even better as far as total heat dissipation. Less of a reason to think a three bank would be necessary. Should be much better than your reference cooler. I'm looking to do a mid range system with a single loop. 120/140 CPU, 240/280 GPU. Not really thinking about competitive benching though. Just want nicer cooling than stock with a good look. I have a 95w CPU in mind so it should work out nicely.

This is complicated stuff... now I actually measured up the case I'm not so sure any more... a 360 in the front will likely interfere with the existing 280 in the top. Another 280 in front is the sweet spot I think, but 280s don't seem to be as common as 240 or 360. I really don't want a 240 on the GPU as I don't think it would be enough to be worth the expense.

I'm being braver now and seriously looking at getting random parts, although my main concern remains adequate compatibility. I really want to get this done in one hit.

I don't blame you as it would definitely be better with shipping. You made a wise choice by making measurements. Proper research should get you what you need with compatibility. 120,240,360,480 do seem to be the most common sizes. Or maybe you meant one hit as in having everything you need without having to wait because something wasnt ordered correctly. With the size radiator chosen you may well have to order from more than one supplier. Same as me, I'm thinking themaltake for my CPU water block, but I want swiftech radiators. Ek for GPU. Kinda sucks but really comes down to fittings for compatibility, that will probably your main concern. So G1/4 of course, but then id and od is the next step. Being braver will help. I'm looking at the largest ID I can get with the smallest od, for ease of workability with petg. So G1/4 is pretty much standard. You'll need to choose your inner and outer diameter. With flex hose, I wouldn't get the cheaper harder stuff. If your going the flex hose route. At least mid range hose will be your best bet, less likely to have problems with kinks, or leaks from bumps or transporting the PC if that's gonna happen. For flex, G1/4 for threads, then id of the barb needs to match that of the flex. Od is much less of a concern unless your gonna use compression fittings. Sticking with barbs, good idea to use some type of clamp, but don't over tighten them. For that type of application, I'm a fan of the plastic squeeze clamps.

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Oh, you'll need the od of your flex for the clamps you choose. I have seen people use worm drive but they can bite into the outside of the hose, they are intended for harder material. That's the reason I've suggested the plastic squeeze type. Worm drive are easy to over tighten.

I think I'm getting there. After a long session last night, I think I just about understand EK's range of products before I move onto looking at alternatives. Originally I was looking at their X series kits, but now I confirmed their rads are 65mm that's too thick with a fan and would conflict with my GPU. Up to that point I was thinking I could go X360 to run both GPU and CPU.

Their P280 would be the next choice, but it isn't in stock at anyone I want to buy from, and I could use this as a GPU only loop as originally discussed. Alternatively I could go P360 for a combined CPU+GPU loop again.

The biggest confusion point I had was that in most listings and manufacturer pages, it wasn't clear what fittings you get with the product. I understand that, as people might want to use different hoses or whatever, they don't bundle that with the item. Take EK's reference 980Ti block for example. It looks like it has 4 holes on it to allow for different entry directions, and the instructions show it needs two plugs (doesn't say included) to block off the unused pair. And their higher end rad... has 6 ports on it, but it does say it comes with 4 plugs.

So as a half way solution, I've been thinking if I kinda follow one of their kits as a guideline, but substitute parts as desired, I should have all I need to go together.

Would it be overkill to get two 280mm rads for a combined CPU+GPU loop? Or would I be so far down the point of diminishing returns it wouldn't be worth it? Given the startup costs of adding a loop, an extra rad wouldn't be significant.

Proposed shopping list would be:
CPU block
GPU block (leaning towards EK 980Ti reference full cover, any real world difference between copper and nickel versions or just cosmetic?)
280mm rad x2
140mm fans x4 (I can reuse existing, either Corsair SP or Noctua)
Tubing as necessary
Fittings as necessary
Pump
Res
Coolant additive

The 6700k (not overclocked, running 8 thread moderate distributed computing load) is currently around 60C with a 280mm AIO. I think the limitation is more likely transfer from CPU to block than the rad area in this case...

If pricing drops enough, I might consider a 2nd 980Ti later on although my 750W PSU might not be up to two of those overclocked.