Slk 3700 BQE ---What am I missing ? HELP

Tad G · Post by **Tad G** » Sun Jun 27, 2004 1:53 pm

Over the last few days my temps have been stable at the following values:

CPU @ 118-120 F (47-48 C)
MB @ 95-96 F (35-36C)
HDD temps @ 100-104F (38- 40) C

(CPU and MB temps taken with ASUS Probe on P4PE, and HDD temps taken with DTemp)

Ambient room temp is 71 -72 F

Today I added a front fan---- A 92mm Panaflo L1a, volted @ 5V through the Molex connector. (and YES, it is blowing inwards toward the drive cage !)

Now, my drive temps are HIGHER than before. 112-114 F

I GAINED temps by adding a fan ?

Ambient room temp is still the same.

What did I not understand here? Somebody just wrote to another poster that any fan, 80-92mm just blowing across the HDD's is a good thing.

Did I waste all this time for nothing? Seems my unit was better off with NO front fan.

HELP PLEASE

Edit: Found a plastic wire tie had lodged in the rear case fan during all the construction.(embarrassment)
After running for one hour:
Still have the same CPU temps, and MB temps.
HDD temps are lower by 2 F.
Should I use a different fan? Or volt this one to 7V instead of 5V?
Thanks.

MonsterMac · Post by **MonsterMac** » Sun Jun 27, 2004 8:01 pm

Perfonally, it really depends on the kind of case you have and how much air is being blown out the rear of your case. For me, I have a case very similar to the 3700BQE and I have one 120mm fan blowing out and no fan as an intake (just a 120mm hole in the fornt of the case). Because of the negative case pressure, enough air is being drawn into my case to sufficiently cool my components. The key thing adding a front fan does is cool your hard drives, if they run hot. Most of the time I've found that a fan in the front is not usually necessary if you have enough fans blowing out of your case (unless your hard drives run hotter than you'd like, then having a fan as an intake blowing across the drives would help you). This is why when your panaflo is running as the intake in your machine, your cpu/mainboard temps stay pretty much the same because they panaflo isnt drwawing that much more cool air into the case than before when you had no fan there. The main thing the 92mm fan is doing for you is providing a source of actice cooling for your hard drives (I feel this is not necessary for me becuase I only have a Samsung SP120gig ATA drive that doesnt run very hot since it's right in front of the intake in my case so enough cool air is being pulled across it). Hopefully you'll understand what I'm trying to stay here, I'm not that great at explaining things. Maybe someone else will further help clarify what I'm trying to say.

acaurora · Post by **acaurora** » Mon Jun 28, 2004 1:34 am

From my understanding, there is positive/negative pressure, the only two types you can have in a case. I'm unclear which is which, but it sounds to me that depending upon the pressure, if you have too much air going in, and not enough going out, the air gets warmed up and then just stays in your case, creating a WARMER environment, rather than a cooler environment. One tip you may want to consider is that to have fans that complement each other. For example, I have the stock antec fan which moves ~ 40 CFM out, and then a Nexus Real Silent case fan which also moves nearly 40 CFM in. The PSU's vents suck air, so technically I have more air going out than going in, but I am leaving the gaps of the drive bays to accomodate for that. To me, that seems to be the favorable solution, to have air going in at the same rate that it is going out.

koody · Post by **koody** » Mon Jun 28, 2004 2:32 am

I was really baffled by your post at first, as it seemed to go against all logic, commons sence and experience. Luckily the explanation was something as simple as a jammed fan

I've read in several places that a front fan generally only affects drive temps. I'm guessing that it's because the amount of air that gets pushed through the case doesn't really change that much if the intake wasn't restrictive before (ie case wasn't starving for air).

acaurora:
Negative airpressure means that you are activly pushing less air in to the case than you are pushing out of it. This results in that the pressure inside the case being lower than the ambient. On normal systems the most air is taken in through the front intake and blown out by the case fan and the PSU fan. If the front beazel is very restrictive the case will suck air in from every nook and crannie (hole) it can, bringing in dust like a vacuum cleaner. The worst case scenraio is air starvation witch means that the the fan is unable to move air since there is no way for air to get in to the case, causing low airflow and possibly a lot of turbulence noise.

Positive airpressure is the opposite of negative airpressure. Most cases don't have positive airpressure. Positive airpressure comes with the benefit that it doesn't collect dust in the case as easily. It's especially useful when you have a filter in front of the intake since when all the air is sucked through that intake you can be sure that your computer will remain dust free. The small holes in the case will not let dust enter since the pressure inside the case is higher than the pressure outside the case ie. the case is blowing air out of the holes.

You can have neutral or balanced airpressure by balancing the amount of air moved by fans blowing in the case. The benefit of this compared to just having positive or negative pressure is negligible unless you are afraid of airstarvation, but that should never be the problem with a normal case.

When making modifications remember that unless you use ducts, the air will not necessarily move the way you want. What I mean is that by reversing the case fan so that it blows in, you have perhaps acceived positive air pressure, but might have worsened general airflow. You are blowing out air through PSU that you just sucked in through the case fan. Now the air will travel a very short distance and your motherboard and hd temps will definietly go up.

Tad G · Post by **Tad G** » Mon Jun 28, 2004 4:39 am

Yes, I have the ANTEC SLK-3700 BQE, with the stock rear fan. Seasonic Super Tornado 300 revision 3 power supply.
The rear fan is volted @ 5v through the 4 pin molex connector.
The front fan (in front of the drive cage) is a Panaflo 92mm L1a, volted @ 5v thru the 4 pin molex connector.

CPU is a P4 2.66B Northwood
MB is an ASUS P4PE

Heatsink is Thermalright SLK-900U with a Panaflo 80mm L1a fan`@ 6 volts with a fanmate.

Arctic Silver 3.

Memory is 2x Corsiar CMX512-3200C2 @2-3-2-7

HDD Maxtor 120GB Diamond Max 9
HDD Seagate 7200.7 120GB

My temps are basically the same, with-or-without the front fan @5V. In fact, I believe they may be slightly higher WITH the front fan by 1C (2F).

I'm thinking of volting the front fan up to 7V.

What's the consensus on this?

glisoni · Post by **glisoni** » Mon Jun 28, 2004 5:22 am

Well, since you allready have rear 120 and another 80 in PSU, one you are adding at the front @5V can not possibly provide enough air to create positive pressure in case. So, I guess that is the reason you do not see any change i temps. Most of the air allready came in to the system through that same opening in front, most likely faster than now, with Panaflo.

Witn 7V in front, you will push more cool air in, and that should make some difference, at least on your hdd's. If you do some ducting (hope it is the right term - closing all the holes in the case that are not ment to be holes - like small openings on front) you will see even better effect, because air will go only the path you choose.

Post by **Ralf Hutter** » Mon Jun 28, 2004 5:28 am

Tad G wrote: I'm thinking of volting the front fan up to 7V.

What's the consensus on this?

Try it.

It's real easy to do and it's reversible if you're not happy with it.