Ducting Mod Questions?

Ok, well I plan on doing a ducting mod soon, and I had a few questions. This is basically for the "family computer" downstairs,l so I want to make it as quiet, cool, and stable as possible. One obstacle to all of this though is the fact that we don't have Air conditioning, and although it usually stays naturally cool in the house, it can get pretty hot once we really get into summer. What I want to do is use an SK-7 on a DLT3C 1700+ which I will be undervolting at stock speeds if possible. I plan on using a 120mm fan in the side of the case to draw in fresh air and blow it directly on the heatsink through a duct. My question is, where do I place the fan in this whole setup? Do I just attach it to the inside of the case panel, and then run a duct from that to the heatsink? Also, considering that I want to duct a 120mm fan to an SK-7, what should I use as a duct? Would some kind of dryer lint tubing work, or should I try to make one out of cardboard and duct tape that will focus the air down onto the middle of the heatsink? One last question I have, can someone recommend a 120mm fan that I could hook up a rheostat to and would move a good amount of air, while being very quiet. I'm not really sure how many CFM's I really need for an undervolted low voltage 1700+ at stock speeds with an SK-7 for a heatsink.

I realize I have lots of questions, so if I confused the hell out of anyone, I'm sorry.

anything about 4" in diameter should work. I used a 4" pvc coupler cut down. I've seen people use glad containers, duct tape and cardboard, just about anything that is going to direct the air from the side to the cpu. If you use dryer tube, don't use the vinal kind with the spiral wire cause that would probabally cause too much turbulance.

As far as placement - get that fan as close as you can to ligned up with the heatsink. If you want it to run quiet, you can do a 7 volt mod on it. Do a search, you'll find it.

Just about any 120mm fan will move a decent amount of air. I'd go with something in the 3,000 rpm range and a rheo will make it un-noticable. Even low speed 120's (2400 rpm) will move a lot of air with very little noise. If you're going to do the duct, make sure the one on the case will be moving at least as much air as the fan you have on your heatsink.

I did pretty much the same thing you are doing, but on a dut3c 1800+ which is gonna be hotter than your 1.4v 1700+ or whatever vcore you end up using.

I put a dryer vent duct from a hole in the case wall to the sk7 with 1) a fan in the case wall and no fan on the sink, then 2) a fan in the case wall plus a fan on the sink, then 3) just a fan on the sink and no fan in the case wall. The last situation cooled the best of the three. I then undervolted that fan (it was a standard case fan, not sure of the cfm) to 5v and it keeps temps below 42C at all times despite being pretty much silent. I then used the 5v mod for the psu fan and the one exhaust fan and now the only thing I can hear is the wd hard drive.

If you use a 120mm fan you'll get more cfms but you may have low air pressure if the fan is some distance from the sink itself. Whatever your duct is made of, make sure it has smooth sides to it and gradual funnelling so that the air doesn't bounce around within the duct. That's why I think you may be better off just using a 80mm on right on the sk7 itself

JohnOh. I am planning to do a similar duct mod in my upcoming rig and I'm glad I found your results as I was going to use only one fan attached to the case and have it push through the duct to the HS. You said, however, that having the fan directly on the HS produced better cooling results. I have a Q for you though. What was the noise/cooling ratio of this compared to #1?
I have always heard that ducting from a case fan to the HS without a fan ON the HS is much quiter. Did you find this to be the case? I'm looking for the coolest and quietest setup possible so I'd like some input since I'll be using thermoformable plastic and once I have it setup one way, it will be difficult to set up differently.

Thanks!

If you don't have a budget issue, consider h2o cooling. I saw a pre assembled kit for under 100.00. h2o cooling is very quiet and would give you lower temps in the summer. I have no experiecne with this retailer, I am not necessarily recommending them but ...click here

I have seen that duct before, pelikan, it is very nice.
However I think I'm going to duct mine from the back of the case (from a fan that would normally be an exhaust) to the CPU like that one guy (sorry, lost the link to his page to show you!)

However after reading that having the fan on the heatsink rather than in the back of the case improves temps, I don't know what to do. I know that moving the fan a few mm's from the heatsink increases performance because of no dead spot in the middle. So maybe the ideal setup is a duct that runs to a fan that is ducted 30-40mm from the heatsink???

I was thinking of running a cheap water setup, but It's just the family computer, so I don't want to spend more money on it then I have to. Besides, I just ordered an SK-7 from svc.com for $16.99 on sale.