Anyone run a panaflo H1A or M1A at 7v?

[kly1222]

If so, how loud is it compared to the L1A model?

Also, is it true that the airflow will be cut in half compared to it running at 12v?

Thanks.

 

[GiZzO]

I'll test this for you, got both L1a's and H1a's here and i can compare em side by side. The L1a i remember doesn't really like running at 7 volts many of times it wouldn't start up, you'd have to give it a little push to get it going. I'll try 5 volts also.

GiZzO's Fan Page

 

[GiZzO]

The H1a at 7 volts airflow is less, the noise of it if ya put it right up to your ear to hear it, is deeper then the L1a but i think its also louder. Im not a big fan of doing the 7 volt trick id rather run it at 5 volts, having two positive wires going off to the fan and the 5v acting as a ground, can cause some wierd effects to your PS. As i noticed when i connect the fan too 12v+ and 5v+ the PS fan you could hear slooow down considerably. Might not be damaging to the fan but could be to the PS, and who knows what other negative effects might be going on. Just to let ya know im using a high quality major brand PS... Sparkle.

 

[kly1222]

Hmmmm...thanks for the info. Now I'm not to sure if I wanna try the 7v trick.

So you're saying the H1A has less airflow at 7v than a L1A at 12v? And that it is louder but has a lower pitch to it than the L1A?

Looks like I should just get the L1A's and run 'em at 12v.

Thanks!!!

 

[Kusta]

This is the word from PC Power and Cooling:

The noise problem is not the fan but cavitation due to intake air restrictions or, exhaust air restrictions from the case fan grill. Also, A fan will not start consistently at 7 volts since most are not guaranteed to start at much below 9 volts DC. Lastly, you would trip the overvoltage regulation of the +5 Volt line, in our supplies. The only universal way to regulate the voltage to a fan is to use a rheostat inline with one lead of the fan to induce a variable voltage drop to the fan.

 

[Jhhnn]

Using the voltage difference between two different rails of a psu is really very common in electronic equipment, no big deal, within the specified load limits. The higher voltage input augments the delivery of power to devices wired between the lower voltage and ground. When using a fan at 7v, for example, there must be sufficient load on the 5v line to prevent overvoltage shutdown. This is normally not an issue, there's lots of load on the 5v line in a PC. This is also linked to voltage regulation, something that power supplies do poorly at very low load. In the example where the psu fan slows down when a 7v load is added, I suspect that the new voltage is actually better regulated, closer to spec.

It's an easy & inexpensive way to quiet overcapacity fans, something all novice overclockers seem to buy. While it's true that not all fans will start reliably at 7v, fewer will do so at 5v, making 7v a better compromise. Not hard to find out, if it starts twenty times in a row, it's good to go. I have two fans running at 7v for over 6 months, no problems. Even tried 8.7v, but it didn't quiet the fans enough to suit me.

Wouldn't it be nice to be able to pick the right fan the first time, the one that will do the job with the least amount of noise? Only in my dreams...

 

[dalilama]

i would go with a rheostat..i have a friend who makes them pro for a company...only a few bucks and does an awesome job. i can hardly hear my setup with it @ 30% power.