Heatsinks on Mac Pro RAM?

[warragul]

Bought a Mac Pro online. 2008 2X2.8GHz 8-core. Runs El Capitan, but not (unmodified) Sierra.
There are a couple of upgrades I’ve looked into but the one that’s bothering me now is RAM.
I’ve bought 32Gig of the right stuff but it came without “heat spreaders”. Why we needed a new
name for heat sinks is beyond me. And why not “thermal dissipators?
The available literature is very confusing on this. Do I need them or do I not?
Apple has a Tech Note TN 2156 that says they are necessary, if only to keep fan speeds in check.
Interestingly, there is a reference in the Tech Note to MO-256 FBDIMM Heatsinks.
New heat spreaders of that design cost as much, if not more, than the RAM.
On the other hand Tom’s Hardware says they are only necessary if you’re overclocking the RAM.
The “heat spreaders” selling online are way flimsier than the Apple Approved ones that came with
the RAM installed on the Mac Pro. The only option I see is to transfer the “spreaders” from the
installed RAM to the new stuff. Then there’s the thermal conducting plastic adhesive strips to consider.
If they behave like normal double-side tape things are going to get messy.
Anyone got any better ideas/info/experience?

 

[fendersrule]

Just from second hand (grain of salt) you do not need them.

 

[Sko]

I bought cheap RAM off of eBay with heat spreaders and it really sucked. RAM temperatures were almost always north of 80°C - that's where the fans kick in on my 2,1. I tried to mount different heat spreaders, thermal paste and thermal pads. I had to learn that most of the time it just wouldn't fit. The AMB was never flush with the actual RAM chips, there was always a gap between the HS and the AMB or the HS and the RAM chips.

I decided to go another route and bought some very, very cheap server pull 4 GiB RAM modules from a local IT service company. It came in sets of four, so I bought two sets, one label as Dell and one as HP.

The temperatures where exactly on the edge, hitting 80°C every so often. What I finally did was adding tiny HSes directly on top of the AMBs with thermal conductive adhesive tape. Now I have temperatures in the low seventies.

Long story short: some tinkering may be required with or without the large Apple-style heat spreaders.

 

[warragul]

Thank you, Sko. Just what I needed. I saw those small heatsinks when I was searching eBay for heatspreaders.
Never occurred to me that cooling the AMBs would be enough.
Again, thanks.

 

[orph]

i think it's fairly normal for people to use puled server ram in 1.1/2.1/3.1 and 667mhz speed too as it's cheaper with minimal slowdown.

cool idea sticking on some extra heat sinks @Sko

 

[ReanimationLP]

I did the same exact thing @Sko did in my 3,1. No issues, prevents the fans from ramping up.

Of course, now I'm about to retire it for the 4,1 I got for cheap once I drop X5690s into it... unfortunately the seller didn't pack it properly so the handles got smashed, but he refunded me about half the cost of the computer.

Spent almost as much on eBay for a case that's not messed up as I did on the computer. lol

 

[EmlynDewar]

SNIP

Think there's not too much you can do with DDR2 FB-DIMMs, they've always ran as hot as the sun and needed some airflow to avoid death!

 

[AlexMaximus]

Bought a Mac Pro online. 2008 2X2.8GHz 8-core. Runs El Capitan, but not (unmodified) Sierra.
There are a couple of upgrades I’ve looked into but the one that’s bothering me now is RAM.
I’ve bought 32Gig of the right stuff but it came without “heat spreaders”. Why we needed a new
name for heat sinks is beyond me. And why not “thermal dissipators?
The available literature is very confusing on this. Do I need them or do I not?
Apple has a Tech Note TN 2156 that says they are necessary, if only to keep fan speeds in check.
Interestingly, there is a reference in the Tech Note to MO-256 FBDIMM Heatsinks.
New heat spreaders of that design cost as much, if not more, than the RAM.
On the other hand Tom’s Hardware says they are only necessary if you’re overclocking the RAM.
The “heat spreaders” selling online are way flimsier than the Apple Approved ones that came with
the RAM installed on the Mac Pro. The only option I see is to transfer the “spreaders” from the
installed RAM to the new stuff. Then there’s the thermal conducting plastic adhesive strips to consider.
If they behave like normal double-side tape things are going to get messy.
Anyone got any better ideas/info/experience?

The 2008 Mac Pro is still an awesome machine. For proper cooling, I would just add a ram cooler. You may want to consider this one here, its the only one that works for the Mac Pro.

http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&product_ID=174&ParentCat=408

 

[hungry ghost]

I bought cheap RAM off of eBay with heat spreaders and it really sucked. RAM temperatures were almost always north of 80°C - that's where the fans kick in on my 2,1. I tried to mount different heat spreaders, thermal paste and thermal pads. I had to learn that most of the time it just wouldn't fit. The AMB was never flush with the actual RAM chips, there was always a gap between the HS and the AMB or the HS and the RAM chips.

I decided to go another route and bought some very, very cheap server pull 4 GiB RAM modules from a local IT service company. It came in sets of four, so I bought two sets, one label as Dell and one as HP.

The temperatures where exactly on the edge, hitting 80°C every so often. What I finally did was adding tiny HSes directly on top of the AMBs with thermal conductive adhesive tape. Now I have temperatures in the low seventies.

Long story short: some tinkering may be required with or without the large Apple-style heat spreaders.

I've been having problems with my Mac 2.1 shutting down recently with no warning. Went through various fixes (replaced PRAM battery, reset SMC button on the logic board, swapped video cards, tried all manner of RAM configurations). Now using the Macs Fan Control app; nothing major I don't think but RAM riser slot A is getting to near 80ºC at times.

I also bought some cheap non-Apple RAM (HP) last year to add to the standard Apple units. I did read the various pros and cons beforehand, and saw enough people saying heatsinks weren't necessary. But I am going the Sko route and have just ordered some mini ones off eBay to stick on.

For now I've moved the Mac out of the corner of the room and am running it with minimal RAM and the side panel off so the airflow will be improved. So far it hasn't crashed all day. Anyway thanks for this thread and for (I hope) saving me from giving up on my trusty workhorse!

 

[AlexMaximus]

[URL]http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&product_ID=160&ParentCat=413




[/URL]

 

[hungry ghost]

@AlexMaximus — thanks, I did look at that product but it's a fair bit pricier than the heatsinks. If they don't work out though I might consider that as a slicker option.

One question — I'm guessing the exhaust fan is the one to tweak as it's nearest the RAM rather than the CPU fan?

 

[w1z]

@AlexMaximus — thanks, I did look at that product but it's a fair bit pricier than the heatsinks. If they don't work out though I might consider that as a slicker option.

One question — I'm guessing the exhaust fan is the one to tweak as it's nearest the RAM rather than the CPU fan?

I remember doing something similar to my MP3,1's memory. I bought a new set of cheap Apple 1GB 667MHz sticks, cost me $15 several years back, pulled the heat spreaders off them and replaced the thin Crucial server memory's heat spreaders with Apple's. I also used non-conductive thermal paste but then switched to pads. Total cost - $25.

Stock mem temperatures (without fan control) where between 50C and 63C

 

[AlexMaximus]

@AlexMaximus — thanks, I did look at that product but it's a fair bit pricier than the heatsinks. If they don't work out though I might consider that as a slicker option.

One question — I'm guessing the exhaust fan is the one to tweak as it's nearest the RAM rather than the CPU fan?

With the heatsinks already ordered, you should be fine. A Delta of Ten degrees means the world for those especially for the middle controller Chips. The exhaust fan is the one, upping the speed for that will help a bit.
I think you should be fine. The mentioned fan solution can serve as a measure of last resort or as a concept for a diy solution. Very small fans usually are noisy, that’s the only concern I have looking at this for bottom slide.

 

[hungry ghost]

W1SS — good idea, 50º-60º would be a lot more reassuring so I'll see how it goes with the ones I've bought. AlexMaximus — I am not overly keen on running fans higher either so hope this works. Just cleaned front and exhaust fans out but that's now brought another problem (new post)...

 

[w1z]

W1SS — good idea, 50º-60º would be a lot more reassuring so I'll see how it goes with the ones I've bought. AlexMaximus — I am not overly keen on running fans higher either so hope this works. Just cleaned front and exhaust fans out but that's now brought another problem (new post)...

Do keep in mind that I was using 667 and not 800 memory in my 3,1.. 800 run hotter so add 5 to 7 degrees Celsius to the range if you are using them.

 

[hungry ghost]

I may not be able to get a chance to use those heatsinks... think the PSU was the culprit. It was still shutting down occasionally; I removed the PSU, blew (copious) dust out and now it won't get beyond the chime upon startup.

I can find some secondhand units around which are all 980W and have been told 'will work' e.g. https://www.ebay.co.uk/itm/273085258659?ul_noapp=true However on close inspection they seem to have identical power output except for the first two output readings which are 13.6A, rather than the 18.8A on my PSU.

I'm guessing that this means that my eight-core 2,1 won't work with the PSU from the other 2,1 or 1,1 models or can they still do a job? Otherwise it's sadly looking like the end for this machine :-(