Here's one for the overclockers.

Well, maybe not just overclockers, because I am not actually overclocking.

I am rebuilding my everyday box. It has a Q9550 CPU (Core2Quad 2.83GHz). No real fancy GPU, just a NVIDIA GeForce 8500 GT (1023MB)and I specifically don't want a fancier GPU because the machine spends most of the day watching the security cameras for motion. If I get a better GPU it will start thinking something moved if someone in London turns a light on. Its already too sensitive and takes a picture if the sun comes out anywhere in England. OK, so I'm exaggerating, but its already too sensitive.

Anyway, the upshot is that the GPU is not a heating issue.

Now the CPU, with stock cooler fan, doesn't really like it if its on 100% at full voltage for too long. It starts getting hot. (Over 70°c I consider too hot.) So I have got a Corsair H60 liquid cooler for it. I can see the logic in having ambient air pulled through the radiator, and intend to have lots of expelling to compensate. I have a spare 120cm fan. Now for the question for those with a better mind, experience and know-how.

If I use the additional fan to create a push-me-pull-me flow through the radiator I am unlikely to get an exact match on pressure/flow rate. The kit's cooler fan will be plugged into the motherboard's CPU fan socket, and so its speed will vary with the CPU demand. However the other really can't really go in the same socket. So.

Do I put the constant full power fan as the push or the pull fan?
Do I bother adding another fan at all?
Do I put the additional fan through a 'dimmer switch' and attempt to synch them manually when I turn on full power.
Do I plug both fans into the same socket by splicing the wires?

The ASUS P5K-E board comes with a nice 'underclocking' utility which I use to turn things right down during the hours when the unit is simply guarding the house and spending all idle ticks crunching for S@H.

Suggestions please.

Len
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I think I am. Therefore I am. I think.

I don't think a second fan is going to make that much of a difference. since you won't be able to regulate the speed of either fan you are at the mercy of the fan Gods when it comes to CFM. each fan will pull differently so you'd either be forcing air into the second fan or creating a small vacuum. stick with the 1 fan design and check the temps. still to high. try a second. still to high. check the thermal paste or get a bigger water cooler.
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Proud member of TSWB.

End terrorism by building a school

Good point !! (i think)
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I recently tried to install an H60 for a friend, but found the water block was the wrong size for the CPU because of 5 capacitors sticking up from the motherboard.

Since that was a different issue, I would try the system with the fan that came with the radiator. What I would do, is to position the fan so that is is pulling fresh air in form outside the case, and it is going through the radiator, then the fan. The H60 isn't designed that way, but it can be made to work. The reason for this is that any fan generates its own heat, and you can get a little better efficiency by not forcing that heated fan air through the radiator. So you have case, radiator, then fan, pulling air into the case. You may have to remove a pci slot blocker so air will be able to escape, or attach another fan blowing out somewhere.

Steve

Len,

I just wrote and erased "War and Peace". The short version:

With your description of your CPU down-clocked and not-crunching, I can't imagine that the H60 won't cool your CPU very well regardless of one or two fans, and regardless of blowing or sucking.

I've recently installed two H60s on a Phenom and a FX-8120, both are 24/7 crunchers, and both stay cool-enough with one fan, whether it blows into or out of the case. I tried one each way. I put a second fan on one, strictly to "see what would happen" and it did drop the CPU temps by about 2C.

Sucking cool air through the radiator and blowing it into the case seems to be better, but I do have a lot of cool air coming in (three 120mm fans) and a lot going out (a 200mm top mounted fan on one, a 140mm top mounted fan on the other; plus the 140mm PSU fan).

Still, for a non-crunching CPU, I think you'll be pleased with just the one fan plugged into the motherboard header, blowing in. Since it sounds like you already plan to plug the pump into an always full-on power source, I won't mention that.

What I would then watch would be the GPU temps to see if I needed more case ventilation.

Thank guys. Great feedback so far.

The board's CPU fan plug does control speed. The CPU does crunch, as does the GPU. I simply underclock most of the day. So the whole system is hobbled by reduced CPU voltage I believe. (Electrickery is not my strong point.) This also reduces fan speed on all the boards's chassis and accessory fan sockets.

When I want to use my machine for me, as well as S@H I turn up the speed to full. Then, S@H still takes whatever I am not using, so the CPU is running 100% on standard voltage. It is then that the heat goes up. It also usually means S@H gets marginally more CPU crunching done, but less GPU as the old GPU is not up to working for both of us.

If I read what has been contributed so far, a Y plug will allow both fans to work on a single plug. My spate 120 is not a matched fan, and the only reason to consider it is that I have it, so could use it.

I am still tempted to use the additional fan as an always on full power pusher and the stock fan as a puller. If the always on cools the CPU too much during restricted use, the worst that can happen is that ir reaches ambient temperature right?

Len
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I think I am. Therefore I am. I think.

I wouldn't do the push/pull unless the fan speeds were matched and I wouldn't run a splitter off a motherboard header - just in case (unless you can confirm the maximum power draw available at the appropriate header).

Also, if you go for drawing air into the case to directly cool the H60, do check what components you will be exhausting it over....

Finally, power up the H60 prior to fitting. A number of people (myself included) have experienced 'pump rattle' from the self contained Corsair units - and generally the advise from Corsair is to RMA the unit if such noises are experienced. Would be handy to find this out prior to fitting ;-)
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You might want to see what temps one fan will get you before you add a second one. Stock intel heat sinks are notoriously underpowered. I can't imagine that you would need a second fan unless you were doing some serious overclocking or the ambient temperature in the room is kind of high. I've got a i7-2600k running at 4.1 GHz on air crunching 8 WUs 24x7. The temp in the room is around 20-23C and with one fan my CPU topped out in the high 50s and two fans only dropped it about 5C.

My previous PC was a Q6600 running at 3.2 GHz (a .8 GHz overclock) for many years on air (aftermarket cooler) and it never got above 60C. Your heat sink may not be properly seated and that could be causing the issues.

TLDR version: One fan will do you just fine even if you decide to overclock with a H60 unless you're running it in a sauna or attempting to break records.
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Thank guys. Great feedback so far.

My spate 120 is not a matched fan, and the only reason to consider it is that I have it, so could use it.

I am still tempted to use the additional fan as an always on full power pusher and the stock fan as a puller. If the always on cools the CPU too much during restricted use, the worst that can happen is that ir reaches ambient temperature right?

40 C is well within the operating temps of that CPU. I would consider anything under 60C just fine for 24x7 use since tj max for that CPU is probably in the 90s.
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I just got back from the computer shop. I just updated my i7-970 which was pushing 70 degrees C before. It had a 120mm CoolerMaster heatsink and single Noctua 120mm fan previously.

It has now got an H80 on it with two Noctua fans in a push-pull arrangement. Will see how it goes but seemed to be around the 40's (under load) when in the shop.