SS400 is whining out of control in SLK3700AMB case!

[enovikoff]

My Super Silencer 400 power supply is revving way up and getting loud even with my CPU at idle. Its revs also surge in a particularly irritating way. I need to do something about it and I'd love your help

Here's the rest of the system: 3700AMB with rear grill punched and Panaflow 120mmL fan running at 5v; front grill in place - it's the less restrictive newer Sonata honeycomb one; original 120mm Antec fan at 5v in front grill; Athlon64 3200; Zalman 7000A-Cu at lowest setting; Asus K8V Deluxe mobo; Raptor 74Gb and 7200.7 160Gb. My graphics card is in transition, the Radeon 9800 stock unit I'm borrowing is the loudest thing in my system and has to go.

I don't care much how loud the system is when I'm playing a game, so I measure the temps and noise with the CPU at idle.
Here's what I've tried:
- Case open: SS400 fan very quiet at 1350 rpm. Disks at 32c, A64 at 32c
- Case closed, 7000a-Cu stopped: ss400 fan at 1850 rpm with occasional peaks at 1950 - very noticeable. Also disks at 32c and A64 at 50c
- Case closed, 7000a-Cu on low: ss400 fan at 1950 rpm with occasional peaks at 2100 - very irritating. Also disks at 32c and A64 at 37c
- Case front bezel removed, 7000a-Cu on low: ss400 fan at 1560 rpm - noticeable but acceptable. Also disks at 33c and A64 at 33c

Another experiment I did was to turn up the case fan. As I ramped it up, temps in the case and CPU dropped, but the power supply had to speed up to "compete" with the case fan so it could cool itself. This led me to believe that the inflow ventilation in the 3700AMB is constricted, which is why I tried taking the front bezel off. I only have a CD-ROM in the default open space of the top 51/4" bay; the other bays are unused. The other bays have perforated metal in front of them, and I can feel air being drawn in there when the bezel is off. This air must proceed more or less directly to the power supply and cool it more effectively when the front bezel is removed.

This all leads me to wonder if I should enlarge the holes in the front bezel, perhaps by increasing the size of the filter-bypass hole at the bottom as well as adding a slot on each side for air to enter the area of the 5 1/4" bays.

Has anyone tried to make the front bezel breathe more freely? Did it result in more noise? How did you do it?

Are there any other solutions to this problem?

Thanks!

-Eric

[Ralf Hutter]

If that SS400 is a "revA2" you're basically SOL unless you want to bypass the internal fan control and also swap out the fan itself. What makes that silly PSU fan ramp up doesn't seem to have much to do with the case/PSU temp itself because the one that I was messing with would start ramping up even when the case temp was in the low 30°C range and the PSU exhaust ari temp was in the 32-34°C range.

There's plenty of tales of woe regarding that darn rev A2 SS400 here at SPCR. Seasonic took one of the best PSU's you could buy (the rev A1 SS400) and completely ruined it with their "new and improved" fan control circuit. Use the "search" and see what creative ideas people have used to overcome this annoying flaw. Mine was to get rid of it.....

[enovikoff]

I spoke with Vincent in tech support at Seasonic. He's been reading all these articles about the SS400 rev A2 and has offered to replace mine with an SS400 rev A1. He said their engineers were trying to be excessively careful about overtemperature problems and changed the system to rev the fan up periodically to prevent it. He implied that this was because the power supply could and might be used as the sole case fan in the system, and as such this modification would keep the whole system safe and happy. He also said he understood that this wasn't the best for their silent PC fans and he'd be happy to replace my power supply because Seasonic was committed to making their customers happy.

I'm going to take him up on it!

[Maurizio XP]

did you tried without the rear fan?

[enovikoff]

Yes, I tried that but the CPU/MB got quite warm and the heat from that must have leaked up into the PS. The problem is that I'm currently using the Antec "1.6" fan that came with the case, moved to the front and running at 7 volts. As soon as I figure out whether a Panaflo fits there or find another 25mm fan that I like, I'll buy it and try positive pressure again.

[Maurizio XP]

ok.

So with a 12x12 fan PSU is better the keep the rear fan move air otuside the case?