Finally silence

Working a lot with my Blade 150 called “Sparky2” recently, the CPU fan turned out to be too loud, still. So I dug deeper into the matter and it turned out easier than I thought…

SUN -for whatever reason- decided to put a comparably small 40x40mm fan on top of the non-standard heatsink and additionally placed some aluminum spacer around it.
Removing everything revealed a totally standard PGA 370 socket! That’s Pentium III, if you remember… So a quick check in my old-junk-stash resulted in 3 nice heatsinks. I took the full-copper one and mounted a 60x60mm fan on top.
Put everything into place – done (BTW: SUN didn’t use any thermal grease, so did I)… but the bigger fan was still too noisy at 12 volts  🙄

After checking the fan also starts at 5 volts, the decision was clear: Bigger, massive copper heatsink plus bigger fan should be sufficient at lower revs.
There’s no direct 5V source on the Blade 150 motherboard. So I chose the vacant connector for the optional 2nd hard-drive (the closer floppy connector would do, too – but I had no spare cable to salvage).

Simply connecting the fan there wasn’t enough. OpenBoot actually checks for the fan tachometer signal and refrains from booting the system without one connected.
I was already evaluating how to build a signal dummy (a simple 555 timer circuit) when I decided to check if a simple forking out of the signal is enough. So I used a 2-wire cable and put ground and the tachometer signal to the on-board fan connector… and voilá that made the OpenBoot happy. Finally silence!

Here’s a piccy.

  • Purple arrow: The new & bigger heatsink (the old on lies on to of the case, so it looks bigger than it actually is)
  • Red arrow: The original fan connector (it still misses the tachometer signal bypass in this photo)
  • Green arrow: This is where the new fan is connected.

Blade150_cpu_fan

One thought on “Finally silence”

  1. Thanks for the hint on the standard PGA 370 socket! The 40x40mm CPU cooler fan of my pre-refresh Blade 150 (System board 375-3088) was getting annoyingly loud.

    Replacing it by a TR2-M3 SE CPU cooler (80x80mm fan) reduced the noise level significantly (even when running from the default 12V connector). CPU temperature (prtpicl -vc temperature-sensor) seems to run 6 to 8C lower than with the stock cooler+fan.

    The only (minor) downside is that the larger cooler overlaps with the space available for the lower PCI card, i.e. any „full-sized“ PCI-card like the XVR-500 has to go to the middle/upper slot.
    Also, the CPU grounding ring (you call it „aluminum spacer“) doesn’t fit any longer, as the stock CPU cooler was customs made to fit. But since I’m not worried about TEMPEST, this should probably be ok.

    Next up is a replacement of the case fans of the Blade 150 (and of a DAT drive) as indicated in your other „Sparky2“ post.

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