The short of it:

I switched out the BQE's stock PSU's stock fan with an L1A.

The long of it (with instructions for those wishing to follow what I did):

Step 1
Take the PSU out of the computer, leave the switch in the "on" position and let it sit for 24 hours.

Step 2
Observe Antec "warranty voided if removed" sticker, laugh at it, take it off, throw it in the bin.

Step 3
Take off PSU case, try to find out which wires are associated with the fan

Step 4
Realise that the provided fan has 2 wires and plug protruding from the PSU for rpm-sensing purposes, and that there is no way it can be easily removed

Step 5
Use scissors to cut said 2 wires, remove fan screws, unplug fan from PSU, remove fan

Step 6
Realise that there is no space around the fan connector on the PSU board to wedge a flathead screwdriver in there to pry it out; curse a bit

Step 7
Use a combination of side cutters and needle-nose pliers to yank it out, and in the process yank out one of the pins; curse a lot

Step 8
Attempt to put in the panaflo in anyway, and realise that the panaflo's 25mm thickness is 1mm too thick to fit. The stock psu fan's thickness was 24mm; curse even more

Step 9
Spend the next 30 minutes with scissors and sandpaper trying to get the panaflo down to size (yes I actually did this, there was black crap everywhere)

Step 10
Insert (force, rather) the panaflo into the PSU, observe that it doesn't go in all the way, and decide that I couldn't be bothered with the screws since the holes don't quite line up properly. nor the fan grill.

Step 11
Take the needle-nose pliers to the PSU's front grill and bend all the slats parallel to airflow a la Tom Brown - this also gives enough room to bring the panaflo's fan connector through the grill for connection on the motherboard

Step 12
Put the PSU back in the case, turn everything on, notice the silence and then notice a strange humming/vibrating sound.

Step 13
Connect the panaflo to a fanmate and turn the voltage down, observe the humming noise drop dramatically.

/story.

The humming noise is getting quite annoying now, but the overall noise level of the system is down significantly.

Any comments/questions?

Amusing, the trials of others.

I presume the humming is coming from the Panaflo, which is spinning? Could it be that because it is jammed up so tightly in the PSU, the vibrations set resonances in the PSU case and get amplified?

I think that's what's happening yep... I actually stopped the psu fan but some of the noise remained. I think i'll just let it be, it's not _too_ annoying.

Finally got around to getting a hold of some tougher grit sandpaper and sanded a mm or so more off the corners of the L1A so that it fits into the PSU more convincingly. I was even able to put the screws on this time

Noise-wise, the odd low humming vibrating noise associated with the L1A in the PSU is gone.

Damn browser ate my reply

Anyway, I was about to say that I have a 350w PSU from 3700AMB, supposedly the same as yours. Yet mine has 80mm fan and 92mm fan. What did you do with your 92mm fan?

Also, I was able to force the Panaflo in without any sandpaper. Just push harder

I have a related question, what is the best way to mod that 350w Antec PSU. I see several choices:
1) Put 80mm L1A and 92mm L1A instead of stock fans and run at 12v utilizing the same outlets inside the PSU
2) Use a resistor to tune stock fans down to 5v or 7v - which is better? What resistor watt-wise?
3) Use a fanmate to accomplish choice 2

What do you guys think?

Keep in mind I have the PSU and 80mm L1A. I don't have 92mm L1A so if the benefits are going to minimal I'd rather go for stock Antec fans. The trouble, I tried each of them on fanmate, and et 7v the 92mm fan is still very whiney. Only at 5v they are quiet. Does it make sense to run stock fans at 5v? This is the cheapest solution for sure.

Thanks!

ColdFlame: i think your psu is the sl350 - mine is the sl350s. mine came with only an 80mm fan, so our psu's are quite different.

and believe me, i tried very hard and pushed and pushed but the fan didn't go in. i think if i pushed any more i would've broken the pcb

Yes you are right, I need to RTFM. I have SL350.

So, what voltage you run your fan in the PSU at and is it hot at all? I'm surprised to see that it has only 1 fan, maybe your PSU runs cooler than mine. Any ideas?

Faster typists beat me to the Submit button.

i run an 80L at 7v, and yes the air coming out of it is pretty darn hot i keep an eye on my +5v line with mbm monitor though, if that goes below 4.8 then i just turn the fan up a bit.

i think antec designed the sl350s to run cooler than the sl350 (nb: think) hence why it might only need 1 fan.

i think you'll still need to use 2 fans with your sl350, whatever you do, because otherwise air will take a shortcut from your 92mm fan hole straight out through the back of the psu, bypassing all the hot components inside. the sl350s can run with a single fan since there is no 92mm and it has a grill on the opposite side, hence forcing the airflow to come across all the psu components.

Something about fan behavior to keep in mind:

In any given space with one fan pushing and another pulling, the total airflow is the lower cfm of the two fans. Example: 80mm fan pulling 30cfm plus 92mm fan pushing 40cfm: The effective max flowthrough is 30cfm.

I know this sounds weird. It is borne out by both theory and experimentation.

The main advantage of 2 fans in push/pull is that the total pressure is higher, and so can lead to higher airflow than a single fan when there is impedance in the airflow path.

So, a single 80mm fan capable of 30cfm in free air only pulls (say) 20 cfm through a PSU because of the impedances within it. Add a 40cfm 92mm fan pushing, and the actual flow through goes up to 30 cfm.

Bottom line: The 2 PSUs you refer to probably have exactly the same circuitry. The 2-fan version will have smaller HS in order to fit. The 1 fsn version probably has somewhat more open vents on the intake side. If you remove the 92mm fan, close up that hole, open up the venting in/out so the 2 PSUs have similarly open venting, and use the same 80mm fan, then the PSUs will perform very similarly. The single-fan one will have a slight edge when pushed hard simply because the bigger HS will keep it cooler to a higher power draw.

I actually prefer the fan at the bottom of the PSU because it sucks hot air from the CPU.

Back to my question, should I bother with undervolting the stock Antec fans in the PSU or just go straight to L1A (80mm and 92mm)? Thanks

go L1A

Yea but you said your PSU is _hot_ and I don't want mine to catch fire
To me those L1A push no air at all I mean I can't feel it with my bare hand.

Take off the grill. your airflow will go up heaps

Or mount an L1A on the outside of the case, all grills removed. Mine is running at 5v and i can feel it easy - also a great hand warmer.

A different case and psu BTW. It hasnt died yet ....

I was going to do this when I found out the fan wasn't going to fit nicely, but I had sandpaper and scissors nearby so I thought, why not

Chylld,
Two things:
1) You mentioned two wires protruding from the PCB for "RPM Sensing".
After you replaced the fan with an L1A, was there any way to reconnect the RPM sensors, and if so, did they work ok?

2) Step 11 - any chance of a bit more detail? ie. perhaps a pic of the finished product?

Thanks,
Tim.

hoorah another fellow aussie

the fan essentially had 2 plugs, one for power (connected to PSU board) and one for rpm sensing (connected to motherboard).

the L1A that i had didn't have rpm sensing at all so yeh. if it did, i'd be able to feed it out and connect it to the motherboard.

here are a couple of pictures:






(that cable is the L1A's cable)

hmm i'd love to take some more pictures but it's just too much of a pain to discharge it, disconnect everything, take the psu out, open it up etc etc.

Aussies: Today, SPCR; Tomorrow, THE WORLD!

Thanks for that. Yeah, I figured that the RPM sensing would have to go... I've got two L1A's in my system at the mo' (somewhat similar to your system, actually!), so I already live with "Suzie" (my A7N8X-D BIOS voice) telling me that my CPU fan's failed everytime I boot.

Thanks for those pics as well... I was trying to figure out what you meant by "Bending the slats...a la Tom Brown", and now I know

Cheers for that...

BTW, you have a PM too

Tim.

no worries

you can turn that annoying voice off.. i did straight away. scared the *#&@(* bejesus outta me since i had the speakers turned up.

a question about your setup - did you notice any changes after getting the l1a as the rear case fan and putting the stock fan at the front? also, how did you mount the l1a?

cheers.

Yeah I guess I can shut her up now, really only had it turned on whilst doing overclocking tweaks...

I installed the L1A as a rear fan during the build of the BQE case, so I didn't even try what it was like for temp/noise before...
But basically to mount it, I just very carefully pulled the plastic rubber feet from the Antec fan, and used them in the L1A.
The Pana plastic is probably 2mm thinker than the stock Antec fan (as you found out in the PSU), but you just have to stretch the feet out a bit thru the mounting holes on the Pana, and they'll hold it quite nicely...

The REAL trick when building this case was getting the SATA->PATA converters to fit in the side-mounting drive cage! But that's a story for another day...

I'll probably take some tinsnips to the fan grills this w/e... Should I be expecting much improvment in temps? I've already got the front of the case all gaffa taped up nice and tight... kinda looked like it belonged in the Michael Jackson BAD! music-video

Take care,
Tim.

yeh i'd say that you'll get a pretty noticeable temp drop. after i cut all my grills i think i got a 3c improvement all round. (it was either 3c or 5c, my memory fails me)

Interesting discussion guys, Mike wrote,

However with my TP 550 I find that the stock 92mm fan overwhelms the stock 80mm and warm air gets vented out through the "intake" vents. Hence in my foolish pre-SPCR days I added a blowhole to my case.

Have been pondering replacing the stock fans with L1A's but have been chicken as I didn't realize you could drain the capacitors by leaving the switch on with the PSU unplugged.

John

you have a right to be chicken - psu modding can kill you. and yes, leaving the switch on with the psu unplugged will slowly drain the capacitors, but it will take time. you should wait 24 hours to be absolutely certain.

having said that, it's really not hard at all as long as you're careful. i mean, i'm still alive, as are many many other psu modders.

another thing you can do to stay safe is to keep one hand behind your back. that way if you do something wrong, the shock will most likely be limited to just the hand you're using, as opposed to your whole upper body

Fear not Fat Bunny (I love that name ). You could remove or disable and then tape up the 92mm hole on your psu. Then reverse the Enermax blowhole fan from an exhaust to an intake fan running at 5-6v. The 80mm psu fan would then draw in the cooler air from the the blowhole. Works for me anyway. And as far as noise goes, I found that I there is no discernable increase in sound whether my blowhole fan is on or if the fan is off and the hole covered up. But then again, I have a very quiet system, not a silent system.

Are u serious??? psu modding can kill you???!?!?1

damn i feel lucky, i modded my compaq 300W psu like a while ago with a panaflo l1a and i did not wait 24hrs.

in fact, i only waited 10mins

wow

~RaNDoM

yes i am serious

a psu stores enough electricity to kill a grown man even after being disconnected for several hours.

ok, so the for the future. if i want to modd a PSU

what steps should i take to make sure i dont kill myself.

~RaNDoM

In all honesty, just don't touch anything except insulated parts & what you absolutely have to touch. I wait onlyu as long as it takes for me to unscrew the case off after pulling the AC cord -- maybe 30 seconds? I've opened up at least a hundred PSUs & modded maybe half as many. I've never been zapped except deliberately -- with the PSU plugged in & on, I used the back of my hand to check if the HS was live. It was. And now when I want to check this, I use a multimeter.

But I'm a bit of a madman, having been zapped too many times in my youth.

To be really safe, do some google searches on electrical safety, etc.