Question What is this purple substance on AMD Ryzen die?

[desgnu]

My theories:

1. Some glue-like viscous substance to eliminate cross talk.
2. Something thermal/temp related?
3. Other, something for optimization
4. Something that was used during creation of the CPU and was left behind during manufacturing

Other's theories:

1. Obfuscation/censoring for the Chinese press released image
2. Bio-neural circuitry from Star Trek
3. Something about us being in a simulation
4. Transistors crammed together making funny looking purple gunk

5. Damage to the die when the soldered-on heat spreader was ripped off.

Source: I can't find the source of the image, but it's supposed to by from AMD.

 

[drea.drechsler]

My theories:

1. Some glue-like viscous substance to eliminate cross talk.
2. Something thermal/temp related?
3. Other, something for optimization
4. Something that was used during creation of the CPU and was left behind during manufacturing

Others theories:

1. Obfuscation/censoring for the Chinese press released image
2. Bio-neural circuitry from Star Trek
3. Something about us being in a simulation
4. Transistors crammed together making funny looking purple gunk

Source: I can't find the source of the image, but it's supposed to by from AMD.

Left out:

damage to the die when the soldered-on heat spreader was ripped off.

And admittedly ignoring Occam's razor yet always a possibility: these are missing circuit elements that time warped to a parrallel dimension when overclocked to far.

 

[desgnu]

Damage to the die when the soldered-on heat spreader was ripped off.

Is that a theory or the answer?

 

[drivinfast247]

That's the magic. The stuff that makes CPUs work.

 

[Nemesia]

That's actually not a CPU die but a map from the game Factorio 😉

Seriously tho. I don't think a lot of people will be able to give you a real answer.

CPU expert at this level aren't abundant.

 

[drea.drechsler]

Is that a theory or the answer?

OBVIOUSLY just one of the many theories...

Where did you retrieve the picture? there may be an accompanying article that explains it all.

I'd do a Google image search but you're the curious one

 

[jamesh1999]

I know it's an old question but that IS the logic of the CPU. The colours you see are just the result of light interfering as it is diffracted not a different material or anything. Also, you'll see the patterns are identical between cores so it's not just random glue!

The blocky features you can see in an orange colour are all caches. They're regularly arranged because that's just what they are: rows upon rows of identical memory cells.

The orange lines between areas, I would say (not an AMD architect), are your buses.

As for some of the random looking purple bits, I'll hazard a guess at one: in the top right of your bottom picture, there are a grid of purple squares. A number of floating point instructions often have a look up table of values to fetch from and interpolate. These are probably the look up tables which would make that square the floating point unit for the core.

Your other purple weird blobs will be your ALU, control logic, instruction decode, branch prediction etc etc

 

[Joe Z]

As for some of the random looking purple bits, I'll hazard a guess at one: in the top right of your bottom picture, there are a grid of purple squares. A number of floating point instructions often have a look up table of values to fetch from and interpolate. These are probably the look up tables which would make that square the floating point unit for the core.

Your other purple weird blobs will be your ALU, control logic, instruction decode, branch prediction etc etc

The blobby bits most likely look that way due to the nature of automatic place and route. You place critical stuff closer together and then less critical stuff around it, etc. The critical bits act like seed points in crystaline growth.

Apple's A6 die photo got some attention a few years back because they went to the trouble of setting up rather extensive relative placement rules to structure and organize their CPU datapath. I don't think it's a full manual layout, but rather a heavily guided layout. ( https://www.ifixit.com/Teardown/Apple+A6+Teardown/10528 )