Right now this mod is on paper, with one similar prototype running. I'm looking for some feed-back, suggestions, etc.

This new project will have the CPU exhaust completely ducted to the outside, so the PSU will not be exhausting any of the CPU output, only the heat off the board, memory, cards, and hard drives.

I'm using a 120mm Fortron.....and I don't want the PSU fan directly over the CPU area. So I propose to move the PSU 5.5" back into the case, filling in the area between the PSU and the output hole in the case with a square duct 5.5" long.

What I will gain here is having the PSU fan further back into the case, making it quieter. I can pad the duct sides, maybe construct a simple internal muffler. It will be quieter......plus the intake to the PSU fan will be relatively un-obstructed by the CPU heatsink=better airflow to the PSU fan.

The downside is the upper two 5.5" bays will be obstructed, so you could only use short devices in those upper two slots...no big deal.

I've done this once before..but only moving back slightly (about 2"). I think this new setup would lower the noise output considerably, at the same time increasing airflow. (Since the PSU is so far back, I could remove the output grill completely without any possibility of touching anything with fingers).

So what do you think?

Photos

Your reasoning sounds - ahem - sound, and I look forward to any results. Any idea of the case for this?

Sounds like a good idea. A simple variation (not as quiet/cool) would be to flip the PSU upside down in place and cut out a square hole up top for the new 120mm PSU intake. Although you have to use the usual 120mm back case fan for everything else CPU/HD/video etc.

This would be louder and hotter but easier for a newbie like myself to do . I'd like to see your version tho especially if you can do it "simply".

Well the rear case fan (maybe 92mm) will provide the exhaust for the CPU only....so the PSU fan will be the only exhaust for the rest of the case. I suspect about 6V to the PSU fan should do the trick.....I've already modded the Fortron with an Evercool 120mm plastic fan, set up for external control. It'll run as low as 2.8V, but to cool everything properly will require at least 6V....we'll see.

The PSU duct mod should be fairly easy.....basically I'm thinking of constructing a long thin wooden box enclosing the PSU. On the bottom will be one 120mm opening matching up to the PSU fan. The whole box will be covered with 4mm acoustic foam...and de-coupled from the steel case.

Ahanix D-Box

I have the case already....I got two Ahanix D-Box cases on clearance $20 ea. The rear case fan is 80mm but can be opened up to 92 or 120mm. The intake is terrible, but I'll fix that ok (more modding). The CPU will run fanless (Alpha heatsink) with the rear case fan pulling heat off it through an aluminum duct (already tried that successfully).

I think this PSU mod will be successfull....hopefully very quiet.

I have done almost the same, but with a seasonic 300FS (one 80mm panaflo rearfan). I couldn't get it further back than 4" though. Your case must be a little deeper. In the bottom of the exhaust-duct I put an 80mm panaflo as a case exhaust blowing up. So there are two fans exhausting in the padded duct to the rear of the case. They are quieter than my single 80mm panaflo exhausting straight out the back.
A muffler would make this even more quiet but I don't have the space for an effective one without obstructing airflow too much.
Good luck with your new project. I expect excellent results, as always!

Great ideas! Bluefront, you've really got me thinking now; and peerke, that's the icing on the cake! I was wondering about the ducted Alpha, though. Wouldn't it be better to leave the fan on the heatsink with just the duct going to the back of the case, thus hopefully leaving some of the noise inside? It's the same principal as what you're doing with the PSU. I'm trying to think of ways of not having fans on the outside of the case.

I might try to duct the Alpha with an 80mm fan on the heatsink end.....but if I do that, I'm stuck using a max 80mm. With the fan on the case end of the duct, I can use a 92 or 120mm fan, with the duct funneling down to the Alpha. Running a larger fan on the case end means lower rpm=less noise. It'll be trial and error to find which works better/quieter.

Blue, are you just ducting the CPU's exhaust out, or are you thinking of doing a complete intake-HS-exhaust duct, thereby cutting the CPU airflow off completely from the warm air inside the case?

It doesn't sound like it, since you mention the Alpha, but it may be something to think about, for a couple of reasons:

1. Moving the PSU further into the case also puts it closer to the intake. Intuition suggests that the arrangement may end up leaving more of the warm case near the mobo, where it will get sucked into the CPU HS, rather than going out the PSU. The PSU may be cooler and quieter, but I wonder about the effect on the CPU temp. (may not even be an issue, just a guess)

2. Maybe you only need 1 fan exhausting the case. If the CPU duct is already pulling the case air out, perhaps having the PSU do the same is redundant. (or vise versa) Ducting either of them directly to cool intake air should allow for an even slower fan to be used.

Sounds like a very interesting concept....can't wait to see it in action.

I've concluded that having two large exhaust fans blowing slowly is quieter than one fan blowing faster....IMHO. This d-Box controller can run fans down to 2.8V (it always starts at 11.5V, then drops back to 4.5V, then you can adjust the speed through 10 steps manually). Since the Alpha duct/fan is blowing out, the PSU fan won't contend with much heat. So I should be able to run it very slow.

Do to a very restricted stock front fan setup, I am going to have to modify the intake. It'll have a fan closer to the center of the case, blowing toward the MB......so I don't think there will be any stagnant air pockets anywhere in the case. I'm still working on the intake/HD cooling setup.

FWIW...this d-Box case is virtually the same as the Ahanix Black Knight. The front bezels interchange, as do the side panels. The d-Box has an 80mm fan on the rear, rather than a 120mm. That's about it.....even the fan controllers are similar...

Gallery of d-Box photos Mine is silver, "Sony" blue front, no window.

Ah, I see. Good points. I kinda assumed you had already given that some thought.

Although a completely ducted Alpha would certainly be an interesting thing to behold.....

Well I've got an Alpha 8942 ready to go. But I think it's too short to attempt a complete intake/exhaust duct setup. The 8952 model you have mentioned, might be able to pull this off (fan mounted on the side of the fins)...but I have serious doubts about that. As it stands, the 8942 can handle a Prescott.....so I know it'll work here (no Prescott this time).

Rusty, I really like the idea of a completely ducted HS, but I just can't imagine how it's done. Are there any examples around to look at?

Well here it is....mostly completed PSU duct mod. The computer is still being finished, but I've tried out the fan setup for noise. It's quiet. And even without cutting out the PSU grill, I think the airflow will be ok.

The MB in the one photo is just there for the photo, giving you an idea of how the PSU fan opening looks in it's new position......and how the duct setup will work. The final setup moves the PSU 4 3/4" back. That whole PSU box comes out easily in one piece. So far, so good.

Photos

Good stuff!!

Question :
- how do you make the duct airtight with the top of the alpha HS?

Eagerly awaiting the finished product.

The CPU duct is an old invention of mine....been used successfully before. It's a perfect fit on the Alpha without cutting. The way it fits over the sides of the Alpha pin-fins, mimics the stock Alpha setup. But it works better because of less restriction to airflow. I'm probably going to have a 92mm fan on the case end, blowing out, sucking air off the bare Alpha heatsink....

Aluminum Alpha Duct

Pic 5 really explains the "why" of this mod. Before I saw that one it didn't really sink in why getting the PSU fan away from the CPU was such a big deal. I forgot about your big ol' elbow in there. Now I understand....... well done. (as always)

Why didn't you combine this with your "Fortron Mod" (The one where you put the bottom fan outside the PSU.)
Looking at picture five, there seems to be enough space.

You're right Tibors....You could combine those two mods(other Fortron Mod). And that remains a distinct possibility.

This new PSU duct is really easy to remove.....plus the PSU just slips out of the end of the duct, so if I want to do more mods to the setup, it's easy enough. But I did want to see how this particular mod would perform on it's own.

I hope everyone here realizes the easier the airflow path through the PSU, the easier it is to keep cool, and the lower the fan speed needs to be. Removal of the rear PSU grill would be a benefit, as would moving the PSU fan slightly outside the box.

Better airflow=lower temps and/or lower noise levels. This is true with PSUs and all other aspects of your computer.

That CPU duct looks really clever. How much cooler does it run now?

Chunker....I'm puting this computer together from scratch. This was the first of the mods. Today I'm finishing the new HD/intake mod. So it'll be a while before I can comment on performance.

Most of the mods I post about have already been tested by me...so I know they work. I usually don't try really stupid stuff that has a slim chance of success. I'm just a little guy, with a small workshop, few funds, and not much time. Lately I've been laid up with an ankle injury, so I have more time for computer mods....

I suspect I'll have the whole computer finished in a few weeks.