[stormy]

For sure, drilling should always happen with all boards out. I took them out when I had the whole Octane in pieces.

Hey Jacquest.. I've noticed an odd phenomenon. When I installed the Sycth fan I noticed a really high pitched whining noise coming from the PSU, I thought it was the fan. I removed the Sycth and put in a Fractal design fan, the noise went away which made me think it was definitely the Sycth fan causing the noise. Then I got paranoid due to the low speed of the Fractal fan, so I replaced it with the original sgi fan again - but to my shock the electrical whining noise came back! I'm not 100% sure if I noticed this originally, it might have existed but I probably thought it was the scsi wirring drive noise.

Anyway.. for some strange reason the psu makes a horrible whining noise when high rpm fans are connected, and the sound does not come from the fan, its electrical... wtf.

[Jacques]

Yo,

I've had three psu's all respond differently to 1900rpm Scythe fans. My first Octane with a Cherokee PSU ran just dandy with a 1900rpm fan, no noise. My second Octane made a slightly loud 'whir' noise, my current Octane squeals like a stuck pig with a 1900rpm fan, but a 1600rpm fan is perfectly quiet. This very same 1900rpm fan ran just fine in a Lucent Octane PSU...go figure!

The Octane PSU puts out 8v to the fan header when not in fastfan mode, this ramps to 12v with fastfan. I think some of the Scythe's struggle to run at 8v. if you run the 1900rpm Scythe, do 'setenv fastfan 1' in the Prom console and reboot. Does the squeal noise go away?

The stock SGI fan should only be loud and not make a squeal.

Things to check, did you swap the yellow and red wire on the new fan. Did you overtighten the fan, including the old SGI one? The original fan is loud, but it shouldn't squeal.

It's a bit of trial and error I'm afraid. You could try adding a 2ohm resistor inline of the fan supply to drop the voltage by 1v on that fan to see if a change in voltage helps.

edit again - My squeal was always the fan. I had it hanging out the back of the PSU to test for a few seconds and it was most definitely the fan on mine.

last edit - The original Panaflow (FBA12G12U) is a 2950rpm 12v 0.65A fan, so the 1900rpm Scythe is a slower spinning fan that draws less current at a similar voltage to the Panaflow.

[stormy]

Yo,

I've had three psu's all respond differently to 1900rpm Scythe fans. My first Octane with a Cherokee PSU ran just dandy with a 1900rpm fan, no noise. My second Octane made a slightly loud 'whir' noise, my current Octane squeals like a stuck pig with a 1900rpm fan, but a 1600rpm fan is perfectly quiet. This very same 1900rpm fan ran just fine in a Lucent Octane PSU...go figure!

The Octane PSU puts out 8v to the fan header when not in fastfan mode, this ramps to 12v with fastfan. I think some of the Scythe's struggle to run at 8v. if you run the 1900rpm Scythe, do 'setenv fastfan 1' in the Prom console and reboot. Does the squeal noise go away?

The stock SGI fan should only be loud and not make a squeal.

Things to check, did you swap the yellow and red wire on the new fan. Did you overtighten the fan, including the old SGI one? The original fan  is loud, but it shouldn't squeal.

It's a bit of trial and error I'm afraid. You could try adding a 2ohm resistor inline of the fan supply to drop the voltage by 1v on that fan to see if a change in voltage helps.

edit again - My squeal was always the fan. I had it hanging out the back of the PSU to test for a few seconds and it was most definitely the fan on mine.

last edit - The original Panaflow (FBA12G12U) is a 2950rpm 12v 0.65A fan, so the 1900rpm Scythe is a slower spinning fan that draws less current at a similar voltage to the Panaflow.

Well I thought the squeeling pig sound was from the PSU due to the original making the same noise as well as the Syth. I've ordered a Noctua NF-P12 1300rpm to see how it performs, I do heed your warnings about airflow though. I am going to compare its output to other fans I've got, if it performs well and has no squeely pig I will keep it.

Thanks for the fast fan idea... I might end up trying this out. I'll let you know.

[Jacques]

Your fan needs to shift air around 90-100cfm at 12v in order for it to pull enough air over the components, especially the TRAMS on MGRAS boards.

With Vpro gfx and a single proc you can get away with around 85cfm at 12v as the Vpro cards dissipate heat so much better.

That Noctua only moves 55cfm at 12v, not enough for an Ocatne unfortunately. At 8v it's only going to move around 40cfm. Your TRAMS won't last long, they will cook themselves to death, very fast!

There is an old Neko thread on this I'll try and find later, it provides an alternative fan spec for systems with MXI/MXE.

Edit - here is the link, second post by Dr. Dave

https://gainos.org/~elf/sgi/nekonomicon/...863/1.html

[stormy]

Your fan needs to shift air around 90-100cfm at 12v in order for it to pull enough air over the components, especially the TRAMS on MGRAS boards.

With Vpro gfx and a single proc you can get away with around 85cfm at 12v as the Vpro cards dissipate heat so much better.

That Noctua only moves 55cfm at 12v, not enough for an Ocatne unfortunately. At 8v it's only going to move around 40cfm. Your TRAMS won't last long, they will cook themselves to death, very fast!

There is an old Neko thread on this I'll try and find later, it provides an alternative fan spec for systems with MXI/MXE.

Edit - here is the link, second post by Dr. Dave

https://gainos.org/~elf/sgi/nekonomicon/...863/1.html

Okay thanks I took your advice and I got a 3000rpm Noctua Industrial fan, this should be fine. I have also upgraded to a v12 now instead of the Mgra.

[Shiunbird]

Sorry for the necrothread =)

Do I understand that the env flags make no difference at all?
I wear noise cancelling headphones, but my girlfriend is not thrilled.

My Octane came with kernname=fastfan set. If I remove that, there's no change in noise levels, and also setting fastfan to 1 also doesn't seem to change a thing.

If I remove kernname, the system boots just ok.

Tips?

(I hate being a beginner)

[callahan]

Sorry for the necrothread =)

Do I understand that the env flags make no difference at all?
I wear noise cancelling headphones, but my girlfriend is not thrilled.

My Octane came with kernname=fastfan set. If I remove that, there's no change in noise levels, and also setting fastfan to 1 also doesn't seem to change a thing.

If I remove kernname, the system boots just ok.

Tips?

(I hate being a beginner)

It depends. If you have something installed in the bottom outside XIO slot, you can not disable fast fan. If you don't, it should change the fan speed.

[Shiunbird]

The bottom slot is free.

Edit: and no PCI cage.

[stormy]

Tried fastfan = 0 ?

[stormy]

I just wanna say it's a shame the images in this post weren't uploaded to the forum, they're now unavailable. It should probably be a forum policy to enforce image uploading rather than external hosting images, I know other retro forums enforce this.

Anyway if anyone wants the photo's thankfully they're on archive:
https://web.archive.org/web/202103110102...d-689.html