Airflow in Sonata with a bottom feeding PSU?

Aleksi · Post by **Aleksi** » Thu Jan 06, 2005 9:51 am

Hi guys

I got myself a mCubed T-Balancer a few days ago. I've been experimenting with different airflow amounts and I've come to the conclusion, that there is really something wrong with my setup. Running case fans in different configurations just seem to make my PSU fan ran faster. The starting point (no intake / exhaust fans):

PSU fan is running 1000RPM while idling. The CPU's heatpipe tower exhausts in the direction of the rear fan. The CPU fan is blowing in to the cooler. CPU temps while idling are ~45C. In this scenario, the PSU is exhausting all the warm air from the case. Very quiet, if not silent.

I've noticed the following things while experimenting with the T-Balancer:

- With 5V the rear fan seems to lower the CPU temps, PSU fan is not affected. Apparently the rear fan creates push-pull situation with the HT101. No affect on case or HDD/graphics temps.

- With the case exhaust fan at >5V, the PSU fan ramps all the way up to 1400RPM. I can understand that these two fans are fighting for the same air, but this happens despite how much air I intake to the case. I've tried using a second intake fan wedged under the drive cages. No help.

- Two fans as intake (0-12V), PSU as the only exhaust. Strange, but true: The PSU fan ramps up. Uh, if there is cool air taken in to the case, shouldn't the PSU also be getting more cooler air?

- The Sonata's default intake fan can mostly be used for cooling the HDDs and the graphics card. Does it help with the case airflow? No. It has minimal effect on the PSU fan (50 RPM) or CPU temp (1C).

The point with my rant is, that the case fans in my case

just lower the component and case temperature. But by lowering the component temps, should the PSU intake cooler air? So, why isn't the PSU fan slowing down? After I experimented with the airflow, the best result was a INCREASE of 100 RPM in the PSU fan. And this ranged from all exhaust to all intake configurations.

Please, any suggestions and ideas are truly appreciated. I'm starting to think I should just let my PSU exhaust all the air and let the components fry

I just cannot believe, that increasing intake doesn't help lowering the PSU fan? And if it doesn't, there is really something very wrong with the Sonata design.

Best regards,
Aleksi

wooglin · Post by **wooglin** » Thu Jan 06, 2005 10:46 am

I've hard wired my (stock) rear exhaust at 5V, which exhausts most of the heat. The PSU (Enermax noisetaker 365) runs a lowly 700rpm, and rarely ramps up from the heat.

I was checking airflow the other day, by covering up the 'Antec' logos on the sides, and my case temp jumped 5 degrees, PSU ramped up to 1300rpm, but the HD's cooled a couple of degrees.

I think that stock, the dust filter / front intake is nigh useless. My dust filter is as clean as the day I got the case, telling me that there's little airflow coming in the front.

As it runs stock, I believe that 90% of the air taken in comes through the side vents, which basically lets the PSU run cool. I can't remember how well the stock Sonata PSU ran, I pulled it shortly after getting the case to compare it with the Enermax which was definitely quieter.

Aleksi · Post by **Aleksi** » Thu Jan 06, 2005 11:07 am

Well, I forgot to mention that I've covered the Antec holes on the sides and I've done a little mod to the front bezel, that opens it up a little better.

The problem with the side vents is, that it gathers a lot of dust inside the case. That (and the escaping noise) were the main reason why I did those mods. But all in all, I don't think that the covered vents can explain this behaviour?

Mr_Smartepants · Post by **Mr_Smartepants** » Thu Jan 06, 2005 12:56 pm

You and I have similar setups. I've come to the same conclusion but by different means. I will be moving to a watercooling solution in a month or so but for the moment, I run a 7V panaflo L1A for the rear exhaust and a Globe 1202512L with thermistor lead attached to the upper heatsink on my Zalmanized Radeon 9800Pro. Under normal load the globe runs very quiet in the 5-7V range but under gaming load ramps up quickly to keep it cool. I find that the 120mm fan in the Fortron PSU (same as yours) ramps up to medium speed regardless of fan type/position. But when I crank up the rear fan to 12V during gaming, the PSU ramps up slowly as well. Wierd!
Another mod I'm considering later this year is to replace the Fortron PSU with a 400W Seasonic Super Silencer (80mm fan mod) and take off the tape covering the 'Antec' holes and partition the upper case from the lower case so that the PSU gets air exclusively from the 'Antec' holes and the rear case fan exhausts the case air through the WC radiator.

wooglin · Post by **wooglin** » Sat Jan 08, 2005 5:10 pm

Having a bit of fun on a Saturday night... I'll stop wondering why I'm still single...

Rewiring the stock exhaust fan to 7v, result = minimal increase in noise.

Tapped off the antec logo in the door

Covered the back-side logo with TP, temporary dust filter.

End result - a little louder, though I can still sleep 8 feet away from it. CPU dropped 7 degrees, case dropped 2 degrees. It "feels" like there's more air being taken in through the front intake now.

Hmmmm... it's still early. maybe I should clip out the rear grill.