The main goal is getting the inside of
my new computer as dust free as possible.
All of my previous computers needed
to be regularly opened and the dust blown out, the earlier ones I
even had to take them apart to do this and they had no dust filters.
None.
Yes, you can buy filtered cases for
industrial use but they are big, ugly and probably sound like a jet
engine while my design needs to be very quiet and small – well,
small enough to fit behind the monitor on my desk which has specific
size limits since it is in a corner.
The previous PC (7980XE) in place
As you can guess, I don't want glass
doors, RGB or any bling at all either.
The new computer will be built in a
case that comes with dust filters – but these filters are thin
fabric mesh, only effective for larger bits of dust like hair – the
fine stuff just goes straight through and there is a reason for that:
the better the filtration, the harder the fans have to work to suck
air through them.
None of the cases I have seen met my
needs so I settled for the Fractal Define 7 Compact knowing that I
would have to modify it to get what I wanted.
I found a review that suggested that there is not enough front air intake area in the Define 7
Compact case as supplied. Nobody mentioned the total lack of
positive pressure though: it seems that other people don't care if
there are gaps between the fans or if parts of the case block fan
intakes. Some areas of the case have vent holes in places that make
it look like the airflow can easily become circular! I am not going
to have any of that though. The filter box will leave a gap at the
bottom where air from the bottom of the case can be drawn in.
Original case front with fan mounts
My mods will not show outside the
finished case and they should give positive pressure.
Please note that I am not complaining
about the case: I am sure that Fractal made a good case, it is just
that my needs are apparently a bit unusual.
THE CASE MODS
The design uses automotive air filters
(the type used for cabin air, not the engine ones) which will be
sucked on by three 120mm Noctua fans. Finding the right filters was
a bit tedious since the measurements need to be close but I found
something that will do. They are listed as “ Ryco Cabin Air Pollen
Filter RCA294P fits Great Wall X200 2.0DT 4x4” and cost $45.90 AU
for two.
Stage 1
To make sure the filtered air all
goes into the case and provides positive pressure I worked out the
places where the case needed to be sealed off and made patterns for
the parts. I did this with cardboard and used sticky tape to hold
them in place.
Above: Patterns fitted to case
There is the filter box, the lower air
box which seals off the bottom of the case from the insides and two
blanking plates, one to close the hole at the bottom of the door and
one for the inside bottom of the case.
Stage 2
Next I got some ABS sheet off Ebay –
this was not cheap but it is well worth it.
Since it was black I put masking tape
over the sheets where I wanted to draw lines and then marked out the
parts from the patterns I had made on the tape.
The back of the filter box was made of
5mm thick sheet , most of the rest were 2mm and the blanking parts
were 1mm sheet.
To cut the back of the filter box I
first drilled out the fan holes with a 115mm hole saw. This is best
done first since if they are off or you get the plastic too hot it
could ruin it. In a bigger sheet it will be more stable and easier to
handle. Then I cut the outside shape with a saw.
The thinner parts were cut with a
heavy craft knife – clamp a metal ruler over the line you want then
cut repeatedly until it gets thin or the groove gets deep enough that
you can crack it off. Sand and file everything to exact size and you
are done. Note that cut edges will have a raised edge and a V shaped
profile which is why you need to file and sand.
Cut parts. 1- Filter box back, 2 & 3 - sides, 4,5,6 - Lower Air Box, 7 - Bottom plate, 8 - Door Blocker
Stage 3
I taped all of the filter box parts
together with masking tape on the outside and checked that they all
fit together nicely at the joins. Then it was a simple matter of
running superglue ( I used Zap-a-gap) along inside the seams to stick
them together. You don't need a lot of glue and it should run along
the seams by itself, with a little help from gravity.
Once the glue was set I took off the
tape and ran more glue on the outside seams now exposed.
Stage 4
While the glue was drying I got out my
dremel- like device and suitably covered in mask, earmuffs, safety
glasses and gloves, chopped the front of the case to fit the filter
box.
Before I did this I took everything
removable off the case as the metal and paint dust is the type of
gunk that you do NOT want in a PC case. It took an hour or two and
three saw blades but I kept at it and chopped the front out as well
as a small part of the inside so that the filter box would go behind
the case front plate.
After that I filed all of the metal
edges as smooth as possible and then washed the whole case in lots of
water and a cleaning rag to get all of the metal dust off.
This is crucial and I washed it twice
as I missed some corners the first time.
Front of case after cutting
Extra edge area that had to be chopped
Stage 5
I sanded the filter box to get rid of
the glue lumps on the outside and taped it into the case and started
fitting the parts of the lower air box to the case with more sticky
tape, adjusting the part shapes until they all fitted neatly
together.
Then it was a simple task to take the
assembled lower air box parts out and glue them together as
previously described. While that dried I worked on the filter box. I
needed to add some supports for the filters and I had already drilled
holes for some coathanger wire rods across the box for this purpose.
I wanted to make sure the spot in the middle where the two filters
met did not leak and I found an offcut of 5mm that fitted nicely
there. I also made three small blocks of 5mm on the side of the box
where it could be screwed into the case.
By using screws to attach it I could
modify it later and it just looked neater.
Filter Box finished
Stage 6
The lower filter box needed finishing
and a bit of reinforcement but once that was done and filed down
neatly it all looked good. The bottom screw holding the filter box
also holds on the lower air box. Originally I thought of gluing it
all into the case but in the end I got some heavy black tape and used
that to seal the air gaps and fix the lower air box to the case.
Stage 7
The door blanker was glued in, the big
plate stuck inside the case with double side tape and then there was
one last thing to do: The knobs that clip the door on needed to be
shaved a little to avoid hitting the filter box.
Once everything was installed it
looked good. I did not paint the cut areas of the case as it was
more trouble that it was worth – this is not a display case. I
don't expect the metal to rust as it should not get wet.
All parts fitted
After finishing the installation of
everything and testing, it all works just fine, no overheating
anywhere - but then I credit that to AMD making an excellent CPU
with a nice big heat spreader and Noctua making a good cooler to
match it. The new PC has an AMD 3970 CPU and an Nvidia RTX 3090 GPU and it really is a big improvement over the old one.
