Silencing a PIII in a Slotket

wilburpan · Post by **wilburpan** » Sun Mar 05, 2006 1:10 pm

I have an old 750 MHz PIII desktop that I am converting into a fileserver. I made my big first leap into silent computing by replacing the old wind tunnel 300W power supply with a 380W Antec Truepower 2.0. Now I can hear the CPU fan, and am looking to try to quiet this down.

My motherboard is an Abit BE6-II, which has a Slot 1 CPU connector. The 750 MHz PIII is attached via a Slotket, which is a Socket 370 to Slot 1 converter. This system looks like a riser card that fits into the Slot 1, so that the CPU is oriented 90 degrees to the motherboard. For an idea of what this looks like:

My CPU has a standard looking HSF attached to it.

I have a few questions regarding trying to silence my CPU. Some of these are pretty basic, so bear with me.

1. Is it true that Socket A HSFs are completely compatible with Socket 370? If so, this broadens my options.

2. Currently the only fan in my computer is the 120mm fan in the power supply. Would passive cooling of my CPU be an option if this is the only fan in the case? (I can add an 80mm fan to the front of the case.)

3. Does anyone have any suggestions as to what HSFs work well with a Slotket? From looking at my motherboard, HSFs that are too wide will run into the motherboard, and HSFs that are too tall will run into the RAM slots.

openwheelformula1 · Post by **openwheelformula1** » Sun Mar 05, 2006 2:35 pm

I had the same board w/ a 566mhz celeron that ran 850mhz. It was cooled with a dingy little thermaltake heatsink fanless. No problem

BrianE · Post by **BrianE** » Sun Mar 05, 2006 11:39 pm

I don't know if you mean it's really a desktop type case, but if it's a tower you could get creative with ducting it to the PSU, or maybe even mounting a fan to the side panel next to the CPU.

I don't know exactly what's available for the 370, but you should be able to find some pretty big and tall heatsinks available for it that you could run fanless or do something with... the only thing is the Socket A/Socket 370 coolers I saw pictures for all showed a retention mechanism for a bracket. I don't see one on your "slocket" though so I hope you don't need it?

cAPSLOCK · Post by **cAPSLOCK** » Mon Mar 06, 2006 12:33 am

I run my P-III 700MHz without any fan on it (don't look at my sig, I haven't updated it yet). I used to run it at 770MHz with a 8cm fan ziptied onto the side of it, but now I just removed the fan, and had to put it back to 700 to keep it stable. It runs pretty hot, I don't know if it will last many years like this though...

HaloJones · Post by **HaloJones** » Mon Mar 06, 2006 6:50 am

I used an Alpha heatsink which is designed for "suck" rather than "blow" and ducted the heatsink to the rear exhaust fan.

wilburpan · Post by **wilburpan** » Mon Mar 06, 2006 7:06 am

Thanks for the suggestions. Unfortunately, because of the design of the Socket 370 --> Slot 1 adapter I don't have a whole lot of room for a HSF. There's not much side clearance because the PIII is oriented 90 degrees to the motherboard, and there's not a whole lot of vertical clearance because of the RAM slots.

I guess what I'm looking for is a Socket 370 HSF that is a standard size that is also silent.

Techno Pride · Post by **Techno Pride** » Mon Mar 06, 2006 7:12 am

scythe katana?

The heatpipes will be pointing up when installed in a case, although i'm not sure whether it'll hit your PSU or block all your DIMM slots.

Techno Pride · Post by **Techno Pride** » Mon Mar 06, 2006 7:12 am

scythe katana?

The heatpipes will be pointing up when installed in a case, although i'm not sure whether it'll hit your PSU or block all your DIMM slots.

IsaacKuo · Post by **IsaacKuo** » Mon Mar 06, 2006 6:44 pm

I have a number of slot-1 systems with this CPU slot orientation. I've had a 100% success rate with using whatever heatsink was already on the CPU, even if it looks pretty small, and ducting airflow from the PSU toward the CPU heatsink. This involves using a PSU with a bottom intake, and flipping the fan so it blows air into the case rather than sucking air out of the case.

Here's an example:

Single fan madness pt 1 - PIII Gateway

However, most of my PII/PIII projects involved slower processors. Only one of them is faster--a PIII 800mhz (100mhz bus). This one has a small heatsink on it, but it looks like it has a lot of surface area because it's made up of lots of tiny thin fingers. Still, it got pretty hot to the touch just from ducting, so I didn't dare undervolt the PSU fan.

I suggest you try and see how far you can get with the existing heat sink; removing the fan and ducting airflow from the PSU (flip the fan on the PSU). You may find you can get good results like I have cooling your computer with just one undervolted flipped PSU fan.

wilburpan · Post by **wilburpan** » Tue Mar 07, 2006 9:13 pm

Well, I tried passive cooling with the stock heatsink by removing the fan. I didn't try reversing the power supply fan, as the power supply is new, and I don't want to void the warranty yet. My PSU does have a 120mm fan, so I had high hopes for this experiment.

No go. Under load, the CPU temp shot up to 70C within a few minutes, and then my computer started beeping at me.

I also tried to measure around the HSF to see what kind of clearance I have. It's just about 50mm x 50mm x 50mm. I don't think any of the recommended HSF will fit in this spot.

IsaacKuo · Post by **IsaacKuo** » Tue Mar 07, 2006 10:19 pm

If you don't flip the fan, then the only way to get any significant airflow from even a 120mm fan is with a very tight duct. With a 120mm fan, this will represent a serious airflow bottleneck even if it works.

A fan which is sucking air inward sucks air inward equally from all directions. Even large tower heatsinks like the Ninja receive very little airflow from a rear case fan or a PSU fan unless they are very close.

For the small heatsink I take it your PSU has, the 120mm fan of your PSU is not a good fit. Sure, the 120mm fan is capable of generating a lot of airflow, but this airflow is "low pressure" airflow through a wide area.

Rather than try and flip the fan or fashion a good duct to direct airflow, you'd probably do better by rigging an 80mm fan to the CPU heatsink.