Cooling options for a fully loaded IIfx

[joshc]

My IIfx is fully loaded with cards, and it does run a bit toasty in there.

As it stands, it's got the stock power supply fan (it is a IIfx PSU as well, not a II or IIx one). That needs replacing anyway as it is too loud.

The cards are:

Radius Rocket Stage I
Radius Thunder GT/24
SuperMac Spectrum Series IV/24
Asante Ethernet
Digidesign AudioMedia II
FWB SCSI Jackhammer (not yet installed in there but will be soon)

As most of these cards are long, they do block most of the airflow. It's my understanding that the shorter cards should go closest to the power supply.

The CPU and FPU also get a bit toasty, I'm not massively concerned about them, but perhaps a little heatsink and a fan for the CPU would be good.

Has anyone experimented with cooling a big box Mac? @Phipli I seem to recall you've done some mods to yours?

 

[Phipli]

I added a second fan in the gap behind the hard disk on my IIx. I was able to fit a 40x10mm noctua down there (I think there might be room for a bigger 10mm fan if you're lucky), and cable tie it to the metal sheilding. Looks neater than it sounds. Used a splitter on the molex to power it. That vent is absolutely an inlet, so make sure you ensure the fan pulls air in.

Loud psu fan? Thats tricky, it would take a bit of time to find a similar fan. Make sure the blades are free of all dust (it unbalances the fan and makes it loud), and try adding a small amount of oil in the bearing if you can access it. I recently did an LC 475 fan bearing using silicon oil (for sewing machines). I had to remove the sticker in the middle of the fan and under it I could see the bearing on that model fan.

The difference was night and day. Fan was so loud before that I had the computers sound maxed just to hear things. Now it is "normal".

I'm looking for a new fan for the LC though because I'd have preferred to see what type of grease was in the thing rather than put a couple of drops of random oil in there.

Fundamentally though, I think the IIfx PSU fan is always going to be slightly loud. Its doing a lot of work. Some air noise is just going to happen. Improvements could be made by not using a ballbearing fan though.

 

[Phipli]

Heatsink on the CPU and FPU are always going to help

 

[Phipli]

As most of these cards are long, they do block most of the airflow. It's my understanding that the shorter cards should go closest to the power supply.

Hum....

I'd say the reverse. There are vents in the lid, if the long cards are past these, the psu fan will pull more air from the easy path through the lid and not cool the disk / ram / cpu as much. If the long cards are close, they aren't acting like a baffle as much as all air flow has to pass them, regardless of path.

Do you know what the logic was? What is the source for that tip? They're probably right for a reason I'm not thinking of.

 

[Phipli]

Lastly, with a rocket in there and a full quota of other cards, there is a chance you're actually exceeding the PSUs rating, or could do. The rockets use significantly more than the per slot power allowance.

 

[Phipli]

Tweaked my fan dimensions in the first reply to match reality and my purchase history.

 

[joshc]

All good points. I'll try oiling the fan first.

I've got a silenx in my LC 475 and it seems to do the job OK.

The stuff about the short cards going next to the PSU was mentioned on this page, but I don't know his source for that info either: http://longview.be/fun-with-apple-aux-on-a-iifx.html

I'll have to check the outputs of the power supply when it's loaded up, my understanding was that the IIfx has a pretty strong PSU but it sounds like it's worth checking what it's like under full load.

 

[Phipli]

All good points. I'll try oiling the fan first.

I've got a silenx in my LC 475 and it seems to do the job OK.

The stuff about the short cards going next to the PSU was mentioned on this page, but I don't know his source for that info either: http://longview.be/fun-with-apple-aux-on-a-iifx.html

I'll have to check the outputs of the power supply when it's loaded up, my understanding was that the IIfx has a pretty strong PSU but it sounds like it's worth checking what it's like under full load.

When the II was young, most cards were full length so I would expect the stock fan to be able to handle a full length card in the closest slot. The same card in the furthest slot is just as obstructive, except for to the too vents above the slots. Puttling long cards in the furthest slots would likely cool the PSU and carss better, but less air would flow through the rest of the case. My hard disk gets really hot as it is! Thats why I added the second fan

 

[Phipli]

I've got a silenx in my LC 475 and it seems to do the job OK.

I have a fan on the way fir some testing, but it might be quite loud. I'm planning to use the first fan to help me work out what I want I'll look into tge silenx fan.

 

[LaPorta]

The actual Apple documentation, as well as Pina guides, state having the shortest cards by the PSU. The logic is simple: if the fan is blocked by a long card, it will have less draw on the surrounding air. There’s models of air vortices and all such things, but just imagine a vacuum hose: you put it near something and it sucks like crazy, but there is little airflow around the sides. The reverse is true when the obstruction is farther away.

The PSU fans are beasts. My IIfx must have had its replaced in the past, because it’s a stock II unit (no fan speed control). I put in a temp controlled fan speed module, but I worry it doesn’t pull enough at that speed even with the only three cards I have. I am going to replace the fan with Noctua units. Someone not long ago said these fit perfectly:

https://smile.amazon.com/dp/B00NEMG9K6/?coliid=IHJ2ILVR8DJCV&colid=WGHZY1H9XZYH&psc=1&ref_=lv_ov_lig_dp_it

I bought similar ones on sale, they just have less RPM (ok for me, probably not your situation), but have yet to install one.

Of course, make sure the upper vent slots are not blocked by a monitor as well. Lastly, what are you running for an HD? An original 5.25, or some sort of SS option? Having a SCSI2SD in mine left a ton of space where you have better airflow, and theoretically could put in another fan.

 

[ArmorAlley]

@joshc
My two points have already been made:
1. shorter cards by the PSU — allows better airflow
2. replace the HD with an SCSI2SD (or its ilk) — allows better airflow & uses much less electricity (less likely to overpower the PSU)

LaPorta makes a good point about ventilation: place the IIfx in a place where it can be well ventilated and that the vents are not blocked.

Multiple SCSI2SDs set up in a RAID-0 array (striping) for even more speed would be awesome too but I wonder whether you will end up flooding your IIfx's NuBus.
I'm curious as to whether 256 colours on both monitors gives you noticeably faster response times than millions of colours on both on the grounds that you have more than a couple of NuBus-90 cards in there and NuBus can only do 10-20MB/s (acc. to Wikipedia).

Finally, if you are afraid about heat, maybe a thermometer inside the IIfx with a remote display outside would be a good idea. It woudl give you an idea of the toastiness of your IIfx's insides. I don't think that the 68030 reports CPU-temperature.

Do let us know please how you get on

 

[joshc]

Thanks everyone.

Yes, already running a SCSI2SD in there so the only heat is from the PSU, cards and whatever gets hot on the logicboard.

 

[Trash80toHP_Mini]

Are you running the top end Fast/Narrow edition of SCSI2SD?

If you can wrangle a SCSI II daughtercard for the Rocket, even Narrow SCSI II should be faster on the Rocket's PDS slot than will be anything NuBus clock limited I'd think, even Fast Wide SCSI II on the Jackhammer maybe?

It'd be interesting to see how well FWB Jackhammer might work out in RAID config on your IIfx. It's pretty much a PPC era (if not Quadra) upgrade I think and way overkill on 68030.

Rocket's a beast and power hog, but fun if you're using it under RocketShare with dedicated displays for it and the fx if possible. VidCard to Rocket communications above the board controller level with Thunder GT/24 is a good thing.

If Rocket's daughtercard is fastest option, use the JackHammer slot for VideoVision Studio. You'll have all content creation bases covered and using a third display from there is icing on a slotless cake. It's not like you'll be running much on the shared fx CPU, even at 40MHz given a 33MHz 68040 on board. Overhead free RocketWare acceleration mode is faster, but what the heck!

VVS should draw less power and generate less heat than the JackHammer I'd think?