Custom chassis design - comments please!

[murtoz]

Hey everyone,

I've been thinking about and designing my own case (scratch build) for some time now. Main purpose of this thing is to get my system quiet (if that's not possible, I'll settle for very silent!), whilst still having it overclocked.
I currently have the system in one of these, but this is by no means ideal. I spent ages looking for the perfect chassis but have to conclude it doesn't exist (or if it does, I don't have the money for it!) hence I'll have to build it for myself.

Hardware to be cooled:
- Intel QX9650, currently at 3.93Ghz, with Ultra 120 Extreme
- 4x 1GB DDR2 OCZ Reaper PC2-9200, currently at 1170Mhz
- 8800GTX, stock speeds, with HR-03, looking to OC
- Asus Maximus Formula
- 3x 500GB Spinpoints HD501LJ
- Corsair HX520W

Main design principles:
- no direct path for sound from within the case out to my ears. This means intakes at the bottom (fully filtered of course), and exhaust at the back
- inverted ATX design
- ducted for best airflow, and separation of thermal hot spots
- suspended harddrives (that are easy to remove)
- has to be as quiet as possible when idling/low load, but I don't mind a bit of noise when gaming (will have my headphones on anyways). To this end I'll be using the MCubed Tban BigNG, fully programmable 4-fan controller.
- Aesthetics: shiny black plexi & smoked plexi side panel

Here's the design (click for big):


Not sure if it is clear from this pic, but the section with the hdd's is separated from the motherboard area, and has an exhaust fan at the top (the blue rectangle) blowing onto the graphics card

Points I am not sure about:
- In the current design, the PSU exhausts air pulled over the Northbridge heatsink. Will this be too hot, making the psu fan spin faster (and would a fan swap possibly make this quiet)? The alternative would be to swap the PSU over (upside down) so its intake fan pulls cool air from underneath. But then how do I cool the northbridge sufficiently?
- The fan in front of the graphics card: This is about 3/4 inch from the card, with the card halfway down the fan, so half the air from the fan goes towards the card, and the other half towards the motherboard/northbridge area. Will splitting the air like this cause turbulence/sound of rushing air? Also, with half a 120mm fan blowing air towards the gfx/hr-03, and a full 120mm fan exhausting air from the hr-03, will this cause any trouble?
- Is 3 fans enough? Should there be more? Where should they be?
- Any thoughts on a nice design for the hdd suspension? I am currently thinking of a cage holding the 3 disks and suspension that would slide out so you don't have to fiddle with the stretch magic or whatever I end up using inside the case itself.

Any other comments/thoughts/ideas/feedback more than welcome!

Many thanks,
Michiel

[MikeC]

It's a creative mixed design, and a very nice drawing too... but I have my doubts that it would be any quieter than many commercial designs already out there. I have a hard time believing this would be quieter or cooler than any nicely optimized P18x series or P150/Solo case. You're trying to move the air through a number of turns and twists; this reduces velocity and increases turbulence.

I think you'd be better off with one of the above cases, a reduction to 2 drives (instead of 3) and 2-3 very quiet fans running at slow speed.

If the point is to make your own, just go for it, but consider the impedance long tunnels and turns pose to airflow.

ps -- I'd flip the PSU over -- keep it completely independent of the heat from other components.

[murtoz]

Hi Mike, thanks for your comments although it wasn't quite what I wanted to hear
I'll go ahead with the build though, if only for the challenge.
I'll flip the psu over too, but will have to work out where the NB heat will exhaust.
A thought to tackle the long wind tunnel problem might be to put a fan at the bottom blowing the air up, I'll revise my design to include this. I am also thinking maybe of splitting the vertical channel at the front so the graphics has a dedicated channel.

Any other ideas?

thanks,
Michiel

[frenchie]

Hi,
I tend to agree with MikeC.
However, if you use ducts, I tend to think (partly from experience), that a fan sucking air through a duct will be more efficent than a fan blowing through it. Also, it's important that the duct is the same shape all around : always square or always round, not a mix between the two.
Therefore, I'd move the fan that's on the VGA cooler to the rear of the case (same for CPU). It you leave the CPU fan the way it is, I'd make the CPU exhaust hole square.

Also, why don't you get rid of the curve in your CPU duct to make the duct start at the heatsink. You'll get a lot of air resistance out of the way and I don't really see much added value to this (IMO, lots of cool air will get sucked in through your bottom intake and through your CPU whether you have this curve or not).

Another thing, I'm not sure the middle fan is very usefull... Experimenting might be your only way to tell for sure here
That would leave you with 2 fans for the whole system which should keep it quiet.

I really like your "GPU on top" design. It's something that manufacturer should think about since GPUs seem to get hotter and hotter these days. Good idea.

Finally, don't forget to post pics and temps and everything when you're done, I think it's a rally interesting eperiment !!

Good luck !!!!!!!!!

[Strid]

ps -- I'd flip the PSU over -- keep it completely independent of the heat from other components.

I was about to point this out too. You do realize, that this case is HUGE?

A nice drawing too!!

[MikeC]

Any other ideas?

The long vertical tunnel in front doesn't improve functionality over a P180 series design. Why not just make an upside-down mb version of a P180? That would give you the top exhaust for the GPU, which is the main advantage over a P180, and it would work fine if you have a HS with fins on that side of the video card.

Then you could get rid of the vertical duct.

You could still have all the air coming up from the bottom -- but do a duct only from the exhaust side of the CPU heatsink. Make it as big as possible for maximum air intake and min turbulence. Actually, with the PSU upside down (fan facing bottom) you don't need any duct here at all. Position the HDDs in front of the PSU in a config similar to the P180 -- make the space between them at least an inch so airflows easily between them. This would limit you to probably 3 HDDs.

Cut out the bottom-most chamber too; just raise the case up on 1" tall feet--- or have a flange that high with large caps for airflow.

Have a look at the design of the Silverstone TJ06, which bears some similarity to the design I'm suggesting.

[Strid]

Any other ideas?

The long vertical tunnel in front doesn't improve functionality over a P180 series design. Why not just make an upside-down mb version of a P180? That would give you the top exhaust for the GPU, which is the main advantage over a P180, and it would work fine if you have a HS with fins on that side of the video card.

Or a mirror imaged version. Sort of BTX style. That'll give you bottom PSU and have the GFX in the top? Just an idea.

[MikeC]

Or a mirror imaged version. Sort of BTX style. That'll give you bottom PSU and have the GFX in the top? Just an idea.

Yes, that's basically what I meant.

[murtoz]

Hello again, and thanks for all your replies

Hi,
I tend to agree with MikeC.
However, if you use ducts, I tend to think (partly from experience), that a fan sucking air through a duct will be more efficent than a fan blowing through it. Also, it's important that the duct is the same shape all around : always square or always round, not a mix between the two.
Therefore, I'd move the fan that's on the VGA cooler to the rear of the case (same for CPU). It you leave the CPU fan the way it is, I'd make the CPU exhaust hole square.

Hmmmm. I was speaking to a guy at work who used to build AC units and he says the same - fan sucking air through the tunnel is more efficient. I'll have to check for (or make) room for the VGA fan.

Also, why don't you get rid of the curve in your CPU duct to make the duct start at the heatsink. You'll get a lot of air resistance out of the way and I don't really see much added value to this (IMO, lots of cool air will get sucked in through your bottom intake and through your CPU whether you have this curve or not).
Another thing, I'm not sure the middle fan is very usefull... Experimenting might be your only way to tell for sure here
That would leave you with 2 fans for the whole system which should keep it quiet.

Experimenting it will be indeed. I did have a fan in the same place as the middle fan, in front of the cpu, albeit in a conventional ATX case, and along with a duct it helped a lot on gfx temps. But I think I'll have to build the outer shell and shelves (but keep them removeable) and then start experimenting with cardboard ducts and dividers. Lotsa work, lotsa fun!

I really like your "GPU on top" design. It's something that manufacturer should think about since GPUs seem to get hotter and hotter these days. Good idea.
Finally, don't forget to post pics and temps and everything when you're done, I think it's a rally interesting eperiment !!
Good luck !!!!!!!!!

Thank you! I can't take credit for the reverse ATX design though - Lian-Li and others have been building cases like this for years. I think the build is still some ways off, although I hope to start it this year (have to build a desk to work on first though!). Either way, once (if?) I do start the build I'll post a log on bit-tech, and I'll post temps here

You do realize, that this case is HUGE?

Yep, huge it is:-D This is ok though as it can serve as a coffee table as well as pc case . Current dimensions are 645x210x480mm / 25.4x8.3x18.9" (HxWxD).

A nice drawing too!!

Thanks! So far it's taken me 2 main attempts and countless hours in google sketchup. I love that software, and the best thing is it's completely free!

The long vertical tunnel in front doesn't improve functionality over a P180 series design. Why not just make an upside-down mb version of a P180? That would give you the top exhaust for the GPU, which is the main advantage over a P180, and it would work fine if you have a HS with fins on that side of the video card.
Then you could get rid of the vertical duct.
You could still have all the air coming up from the bottom -- but do a duct only from the exhaust side of the CPU heatsink. Make it as big as possible for maximum air intake and min turbulence. Actually, with the PSU upside down (fan facing bottom) you don't need any duct here at all. Position the HDDs in front of the PSU in a config similar to the P180 -- make the space between them at least an inch so airflows easily between them. This would limit you to probably 3 HDDs.

I'll have to try this out I think. My reasoning was that ducting would give less turbulence if the diameter would stay the same all the way through.

Cut out the bottom-most chamber too; just raise the case up on 1" tall feet--- or have a flange that high with large caps for airflow.

Yep, this was always pretty much the plan - just haven't gotten around to drawing it! The idea is to have the shell be the feet but then come back to the first shelf - and the side panels will be cut to follow this shape. Sortof like it is standing on 4 D's. I'll include that in my next drawing.

Or a mirror imaged version. Sort of BTX style. That'll give you bottom PSU and have the GFX in the top? Just an idea.

But that's what this is!? If I mount the atx board upside down on the normal side I'd have the back connectors on the inside;-)

Thanks again for your ideas. I have some drawing to do to incorporate the changes. I'll post an updated pic later this week.

Oh and my mate at work had the brilliant idea of using a pci slot cooler to exhaust the northbridge/memory heat. This may be the only viable option currently to cool the northbridge. Does anyone know of any quiet ones?

Thanks,
Michiel

[Strid]

Or a mirror imaged version. Sort of BTX style. That'll give you bottom PSU and have the GFX in the top? Just an idea.

But that's what this is!? If I mount the atx board upside down on the normal side I'd have the back connectors on the inside;-)

No, because if you flip it the right way, it will be mounted on the opposite case wall, connectors to the back and PCI ports in the top.

Good luck with your 3 GHz coffetable.

[murtoz]

I've also just found this airflow straightener. I quite like the idea and might build something like this to incorporate in my air tunnels. Thoughts?