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Old 28-01-19, 08:44 PM
Nine Iron Nine Iron is offline
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Naked die cooling - worth it? Here's the - well, AN - answer...

Adventures with Naked Die Cooling

This is my go at some naked die cooling - that is, removing the CPU’s heat spreader and mounting the heat sink directly to the silicon. I couldn’t find any details of anybody having tried this so I thought I’d do a write-up myself.

Current setup

De-lidded i3-8350K (daft, yes, but waiting for Ryzen 3) with Noctua NH-D15 (two fans).

Equipment

1. De-lid Die Guard

This experiment was prompted by a chance encounter with a De-lid Die Guard (DDG) on eBay - a metal plate that replaces the motherboard’s locking mechanism, leaving the CPU die exposed. I paid about £15 for it.



(While it would be possible just to drop the CPU in the socket and use the cooler to keep it down, having the cooler load concentrated on the middle of the wafer can - and will – snap the corners.)

The DDG fit perfectly with no collisions at the board level but the CPU die ended up very slightly proud of the plate. That’s easily fixable; the difference can be made up with – no kidding – four dots of Blu-Tac on top. The die not reaching the top of the DDG would have been a game-over because the cooler would stop on the DDG before touching the die.

2. Cooler modding

I knew the CPU was going to lose some Z-height when the IHS came off but conflicting sources left me no way of knowing how much; the best I could cobble together was “between two and four milimeters”. Thus, I had to find some way of dropping the NH-D15, incrementally, to close this gap. (Trying to screw it down further won’t work; it’s designed to bottom out at the IHS.)

Method 1

The D15 screws into two “boomerang” rails, which themselves sit on cylindrical plastic bushings; I found them to be M4 x 11 mm. eBay came through again – I ordered a bag of M4 x 7 mm and M4 x 8mm, as well as some M4 x 0.1 mm metal washers for fine adjustment; this would cover all possible drops between 2 mm and 4 mm in 0.1 mm increments. It turned out to be 3.15 mm in case anybody is curious.



After taking the IHS off and putting the naked CPU in under the DDG I discovered that this wasn’t going to work. The bolts that go through the back-plate are only threaded at their ends and the boomerang rails won’t pass through them to sit on the lower bushings. Thus, the rails will be 11 mm from the motherboard no matter how short the bushings are underneath. Bugger.

After some head scratching, though, I realised the D15 can be modified in another way…

Method 2

The cooler is connected to the boomerang rails via detachable “wings”, and spacers can be inserted between the cooler and these wings to drop the cooler without having to drop the boomerangs. This would need tiny washers, but it’s do-able.

Four M3x0.8 washers on each bolt gives a drop of 3.2 mm (0.05 mm too far, but that’s half the thickness of a piece of paper – good enough), though I had to replace the M3 bolts with slightly longer ones. Bolts and washers cost me less than three quid from Toolstation; before and after:




Research suggested a possible problem with the socket in the form of protruding locator keys – one Youtuber (in fact, the only Youtuber I could find who’d tried this) found that these keys prevented any contact whatever between his CPU and cooler. This affected me as well so I put the DDG in and trimmed everything flush to that with a razor blade. Five minutes work.

Testing

Before using any precious Conductonaut I put a sacrificial blob of boggo thermal paste on the die and tried a D15 fitment. Paste spread perfectly – good to go. Conductonaut down, D15 screwed up tight… will she POST?



Yes! But I nearly forgot to bash DEL and get into the BIOS; a bad contact and the CPU might have melted on its way into Windows. I left it in the BIOS for quarter of an hour to warm up a bit and it was fine. So, into the OS.

Again, no issues – idling in the high 20’s at the desktop. I put some Youtubes on autoplay and nipped to ASDA for an hour, coming back to find an average temperature in the mid 30’s. Okaaaayyy… let’s do the real one: OCCT.

Results

I’ll be brief: for the same fan speed and matched ambients, I cut two degrees off the hottest core and one degree from the others. That’s it. Not even outside the margin. There wasn’t even any difference in the heat-up/cool-down speeds.

Costs

Dosh

Not including parts I ended up not being able to use, I shelled out less than £20 in total; I already had the Conductonaut for a graphics card project, but that would have been another tenner.

Time

Modding the cooler took about half an hour – had to grind a flat into all sixteen washers – and prepping the socket took another fifteen minutes. The CPU having already been delidded made it a lot easier to delid again.

Conclusion

Was it worth it? In a word, no. Nothing was gained over a standard delid and I would 100% advise against setting out to do this to a stock CPU; just delid it the normal way. And this is before the faff of figuring out how to modify your cooling, if it even can be modified; I was lucky the D15 has so much hardware holding it together.

Do I regret doing it? Not really. It didn’t cost enough to bother me (bricking the CPU would have been little more than an annoyance, and I can resell it as a delid), and I had fun solving the problems. What’s more, this is a definitive result: it’s not worth it for this setup. Had this CPU been running near TJmax there might have been enough heat shaved off to prevent throttling, but that’s for somebody else to investigate…

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Old 29-01-19, 10:59 AM
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looz looz is offline
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Great writeup, appreciate the honesty of going "well maybe this wasn't the best mod". Though it's definitely a neat setup now!
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Old 29-01-19, 01:33 PM
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AlienALX AlienALX is offline
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This was figured out many years ago when delidding began. MSI used to bundle them with their boards but yeah, wasn't worth it.

Good writeup though.
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