Archived from groups: alt.sys.pc-clone.dell (
More info?)
"User N" <usern@invalid.invalid> wrote in message
news:TYGdncexYN22WLLfRVn-jg@comcast.com...
>
> "S.Lewis" <stew1960@cover.bellsouth.net> wrote in message
> news:uxOXd.32732$%Y4.16279@bignews6.bellsouth.net...
>>
>> "User N" <usern@invalid.invalid> wrote in message
>> news:Yu-dnduUE7I6_7LfRVn-vQ@comcast.com...
>
>>> How many 4700s would that be?
>>
>> More than I can count.
>
> Hmmm, ok.
Thanks. I make millions by posting bad information to newsgroups just like
this one. <sarcasm>
>
>>>> [] The third would perhaps be that *all* of the 4700's have a
>>>> copper-core passive heatsink (I've noticed that some of the newest
>>>> 3.0+GHz units have the same oversized heatsink/shroud as the Dim8400).
>>>
>>> Just to confirm... the 8400 CPU fan blows air OUT of the case?
>>
>> Absolutely. Not to be confused, while the passive heatsink is identical
>> in these faster, newer 4700's, the fans are NOT the same as the fan in
>> the 8400. The housing and green shroud over the heatsink are designed
>> very similar to the 8400 design, but the fan/shroud assembly is not
>> identical.
>
> Is there anything about the 8400 fan/shroud assembly that would lead you
> to believe they are capable of moving significantly more air or otherwise
> providing significantly more cooling?
>
I've not measured the fan diameters, but they appear roughly the same. The
8400 fan, however, has a far deeper fan and blade. If you experience one of
these fans in an out-of-control state (search this ng for threads if you
like, or the Dell support forums) it would certainly appear to be a far more
powerful fan. It can move light objects off of a flat surface very easily.
All that said, I've not come across CFM specs for either the fan in the 4700
or 8400. Both are variable RPM fans.
> How about the power supplies... IIRC the 8400's is a higher watt unit,
> but are the fan sizes the same?
>
> If the CPU and PS fans in both the 4700 and 8400 provide similar amounts
> of airflow, perhaps a reason for the fan reversal could be found
> elsewhere.
I've not worked with as many 8400's.
I honestly don't know if the PS fan diameters are the same on the units,
though I know that the specs.ratings on the PS's are far different:
Dim4700 specs, including power supply and heat dissipation:
http://support.dell.com/support/edocs/systems/dim4700/sm/specs.htm#wp1043338
Dim8400 specs, including power supply and heat dissipation:
http://support.dell.com/support/edocs/systems/dim8400/SM/specs.htm#wp1052308
With regard to a relentless "search for a reason" the 4700 fan is reversed,
you'd probably be far better off posting the query over on the Dell
community forum (Dimension/general hardware) board and see if the Dell
moderator will respond.
We're nothing but a bunch of users here, very unofficial indeed.
>
>> W/regard to the 8400 hinged case, it also underwent significant vent.
>> changes from it's predecessor the Dimension 8300 (which I worried did not
>> 'breathe' enough).
>> A front vent/'scoop' was added below the 8400 front USB/Audio I/O ports,
>> and additional open grille area was added to the metal on the rear of the
>> case.
>
> The pictures I've seen did give me the impression that the 8400 has more
> front
> vent area and it is less restricted.
I don't know that I agree with that, but I have nothing to base my opinion
upon. The hinged cases have always seemed to me to be more airflow
restricted, while the plastics and actual sheet metal venting on the small
boxes (Dimension 23XX,24XX,3000,46XX, and 4700) have seemed to be less so.
The 8400 case is a huge improvement over the previous hinged systems - but
then again it's much hotter. This heat issue is a big part of what lead
Intel to change direction recently :
http://news.com.com/Intel+kills+plans+for+4GHz+Pentium/2100-1006_3-5409816.html
I'd also add to that that I've not been able to pin any 4700/8400 problem to
heat other than an outright 'thermal event' or 'fan failure'. I suppose the
heat could have a slower cumulative effect on components, but these models
are relatively new.
>IIRC, with the 4700's CPU fan blowing out,
> airflow into the front vent was obvious to the hand but not terribly
> impressive.
> With that substantial grill area on the side, perhaps most of the air is
> coming
> in through there.
I would tend to agree, but again have no proof of such. I've never reversed
any of those fans.
>
>> The heatsink, fan, and fan shroud were all enlarged/improved.
>> Additionally, the "75w video adapter card" limit was added in user guides
>> (online) which calls for an additional "blower" fan to be added to the
>> case above the expansion cards (for PCIe cards that exceed the 75w spec).
>> It also "pushes" air over the cards and out the rear of the system (in
>> the newer grille area).
>
> The card fan is something I've been wondering about. I don't recall
> seeing any
> obvious mounting points in the 4700, and a little digging didn't turn up
> any
> references to a card fan being available for the 4700. Have you heard of
> such
> a beast?
No, and to my knowledge none (OEM) exists. There are plenty of (retail)
ways to mount fans in the system, but those options would almost surely make
the system more noisy.
>
> If one *isn't* available, that would be a significant difference between
> the
> 4700 and 8400. If the 4700's CPU fan is blowing out, I'd expect much of
> the
> GPU heat to be pulled through the CPU heatsink.
That's certainly a possibility. I've seen a few 4700's using the
mid-to-low-end NVidia (fanned) card. They operated satisfactorily with the
fan (obviously) pulling inward.
> If I read your comment
> correctly, in a card fan equipped 8400, GPU heat would be routed out the
> back vent. So what do they do with the 4700?
There may be someone in the group with that configuration, but I've not seen
a 4700 with the top-of-the-line Radeon or NVidia ( 2 slot ) PCIe video card.
Those options (75w or higher card) may not be offered on the 4700 as
ordered. Not sure. But one would guess that the heat would simply be
forced out similarly except with any interference the physical width/height
of the card and it's fan might create (as well as the additional GPU heat).
Perhaps someone can comment more conclusively.
> Will it reject the higher
> wattage graphics cards that would require a card fan in the 8400? Or
> maybe
> they decided to reverse the CPU fan so that it wouldn't be swallowing GPU
> heat?
>
Again, dunno. Since the 4700 has "only" a 305w rated PS (equal to that of
the older Dim8300) perhaps that limits it from using the fastest/newest
cards, many of which whose vendors suggest minimums of 350, 400, or even
higher wattage power supplies.
Someone out there has tried it, I'm sure. I'd look to the Dell community
forum on that one (Dimension/Video group).
As a guess I'd think the 4700 PS couldn't handle the latest/greatest PCIe
GPU needs.
>>> Do you happen to know whether the PS fan is variable speed in
>>> either the 4700 or 8400?
>>
>> To my knowledge they are not. In fact, I feel almost positive that
>> they're not.
>
> OK, well like I said, one or more fans was working harder before I made
> the CPU fan blow out. This was with box out in the open rather than under
> a desk or what not. If the PS fan RPM was the same regardless of CPU
> fan direction, then when the CPU fan was blowing IN, it was working
> harder. I'm not sure what that means, although one possible explanation
> would be that even in an unenclosed space, the CPU fan was drawing in
> hot air that was exhausted by the PS fan.
>
I'm not disputing your claims about fan load whatsoever. Again, I've not
reversed a fan in those systems as I've not had to or felt the need. In
fact, I quite believe you'd see some variance in fan(s) speed(s) when
changing the flow.
Post back if you get some official word from Dell that explains what appears
to be the designed airflow change.
Stew
BsXd.6068$CW2.5781@newsread3.news.atl.earthlink.net...
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