Viewer-Mail Ep8: This CPU Unsoldered and Killed itself

foreign welcome back to another video today another episode of a viewer mail because Max reached out to me several days ago he said that he was running a system with a 7900x everything was working fine for several weeks and from one day to the other like out of nowhere the CPU was showing zero zero well the main board postcode LED was showing zero zero which was kind of like odd but still this could happen right your CPU or mayboard could die and when he like disassembled everything and cleaned everything he reached out to me and said Roman I'm not sure what happened but suddenly I have liquid metal on my CPU even though he did not use Liquid Metal he used conventional thermal paste and I said this doesn't really make sense so please show some pictures to me and what I saw I couldn't really believe it but that's what we're going to check out in a second I just want to point out first that I sent him a 7900x 3D in return so we can take a look at his CPU and at the same time he can enjoy a new CPU and already have fun with his system again hetzna now offers a new dedicated root server powered by a ryzen 7 700 CPU which you should definitely not miss the ax 52 starts at 59 euro per month and is equipped with two one terabyte nvme ssds gigabyte connection and its usual unlimited traffic the powerful 8 core CPU is paired with 64 gigabyte of ddr5 memory by default but can be upgraded to up to 128 gigabyte ddr5 memory and even with ECC if required you will benefit from hetzner's excellent service and of course there is no minimum contract period find out more in the link below so you know what I'm talking about check this out because this looks like a blob of liquid metal but if we touch it it's sold it and we also have some like tiny pieces like directly next to it on the left I had no explanation for this especially when he reached out and showed me like pictures and videos I said this doesn't really make sense like I have no clue what this is but then thinking about it I thought maybe the CPU had like a failure of temperature protection or something like that and this way the CPUs got so hot that it actually unsoldered itself and died that is something I think could have happened and we will try to investigate this now the question is how can we even investigate this because if we would just take a deliver and move the IHS back and forth I have the feeling that we could maybe damage something underneath or at least we could make it look different than what it looks now so I'm thinking about maybe taking the CNC mill and Mill away one part of the IHS and then maybe with the macro macro lens we can take a look like in between and after that I also checked out he was using x670e hours Master which I also have we will try to like replicate this with the same like board and BIOS version maybe check out if there is some issue with the over temperature protection we fixed the 7900x inside this lapping tool and this way we can clamp it inside the CNC and then Mill away like the top area here of the heat spreader now we have the CPU securely fixed inside the device one quick check but that looks good so far right now like two millimeter depth and we still have to go additional like four millimeters into the back because we don't want to damage anything on a PCB or like the chip as a reference we're always double checking with this 7600x that we did quite a while ago because we just don't want to like cut into the chip but also like the depth we're going right now is like 3.5 millimeter and that would not like go into the chip just into the solar worst case now that we couldn't find anything on the iodine like everything looked kind of normal we will try to close in on one of the ccds from the right we now closed in to the CCD on the right and I think same as on the iodine I cannot really spot anything unusual so I think we'll just continue to do the same thing on the left kind of the I would say the most complicated and expensive deleting I did so far or most obscure way at least that's pretty crazy I mean if we just pay attention to the edges like the corners where we closed in to the like the chip with the indium solder all the edges IO die left CCD right CCD seems like there is solder everywhere it's pretty obscure kind of unexpected but nothing was visible at least looking from all the edges for iodine CCD and everything that's the reason why I left the bottom corner so we can still use a deliver and then push away the IHS and maybe look underneath I even have to check because the like solar piece is still in the way if I can even fit the glitter on yeah with a little bit of pressure should work the deleter only allows about one millimeter of movement and you can also see that by the additional amount of like solar that's revealed underneath but that's not enough to like loosen this part entirely might be that we have to go with the traditional wise method you can see got loose mm-hmm I think we were pretty spot on with our first assumption especially if we look at the Heats better the area between the ccds and the i o die there's like this additional piece of indium here this is not normal I've never seen this on any other deleted CPU before and that's also probably why this excessive amount of indium is like hanging off to the side and you can also see some voids inside the folder here like bubbles it looks like bubbles and we see the same on the CPU like areas here and here we have these voids that I've never seen on any other deleted CPU and we deleted a lot of ryzen 7000 this is definitely unusual and since we know that the CPU worked for several weeks I would also say that this was not a manufacturing mistake after investigating my images later I noticed a few more things which I want to discuss with you and first of all we're looking at the CPU in the condition where the Heats better was still attached on a PCB we see some slight damage which probably occurred while one of the like feet of the Heats better got ripped off during the Milling process and at the same time it also ripped off three of the smds but I mean CPU is dead anyway so it doesn't really matter but what we can see nice and clear are the different layers of the CPU on the bottom we see the chip surrounded by underfill that looks like a glue this is two additionally secure the chip on the PCB directly above we can see the solder layer that is contained of indium above we see the 3.4 millimeter thick heat splitter and because we know this thickness of 3.4 millimeter we can easily just do pixel measurement and determine the height of the enum layer and we had about 235 pixels for the heat splatter and about 24 pixels for the indium sheet which then equals about 0.35 millimeter for the indium layer and I know this is not like totally accurate and scientific but even with 10 or 20 tolerance we still know that it's somewhere between 0.3 and 0.4 millimeters now investigating the edges of the iodine everything looked kind of normal I mean that's what I wanted to do with this entire like Milling away the heat sweater checking the edges of the chips and checking the edges of the csds both for left and right they all look good so it's not like all the indium is gone like at least on the edge it looks pretty normal paying more attention to the he's better from underneath we can find more interesting aspects and especially between the area of the i o chip and the ccds because like you can see this gold layer which is for better wetting conditions during the indium solar process and typically this area between ccds and IO is also gold but you can see that some of the liquid India must have flown across this area which is not normal I deleted about 30 to 40 am5 CPU so far and none of them looked like this and not normal are also these holes and craters which we can see on the bottom of the heat spreader and now you could also think that this could be a manufacturing defects some kind of quality issue that AMD might have during production I personally don't think that's the case I don't think that this CPU had some manufacturing defects and the reason for my theory we can find on top of the CPU dies and the same kind of holes and craters which we saw on the heat spreader we can find now on the chip same thing same area and we can also see the like gold layer shining through from underneath from the Chip And one of these holes like on the left the bigger one is especially interesting because if you look at the surface of the indium you can see that most of it is like mud and this is due to like the deleting process where we moved the IHS slightly but this hole you can see it's shiny and you will only get get this shiny surface on the indium if it melted and this is quite interesting because this means that in this area in this hole or Crater the Indio must have been so hot that it actually melted and flew away the odd part is still that indium requires about 160 degrees Celsius to be liquid and at this temperature any CPU is usually dead that's something especially with Skylake X we had several times when we were experimenting with TJ Maxx offset where you could increase the safe temperature from like 105 degrees Celsius to 115 or 125 and a lot of CPUs they would die at 125 so I don't see how a CPU can can see it can reach 160 degrees Celsius it's it's so obscure and also you have to keep in mind that your CPU is also getting cooled that's also like an interesting aspect because he was using an MSI core liquid 280r we know that the 240r and 360r some of them had issue I'm not sure about the 280r but even if like the pump was not working or anything I mean you still have the pump head on there and all the liquid would have to evaporate to exceed 100 degrees Celsius because I mean you have water inside and as long as there's water and it starts to evaporate all of the water would have to be gone to exceed this temperature and it's I would say it's quite unlikely and then still CPUs typically have safety measures inside to not exceed these temperatures which is yeah it's just very odd and if you ever played around with liquid matter for example because going back on these like hot spots and also these empty spots which we saw on the ccds if you use Liquid Metal and you apply it and you forget like one square millimeter you can easily get extreme hot spots and temperature issues you would see a car hitting 95 degrees Celsius and this would cause the CPU to throttle which then again causes the CPU to consume less power which then makes it harder to hit like 160 degrees Celsius which I or which is the reason why I don't think that it's a manufacturing defect it's a lot of factors that go into that that don't really make sense one factor could be the board theoretically some boards could disable these safety measures as I said before he was using an auros master I thought I have one I only have an RS extreme so yeah it's not exactly the same scenario which is unfortunate but just going to use this 7600x on this RS extreme and see what happens if we like take off the cooler while it's running see how the safety measures like react I also want to point out that he was not overclocking his CPU like no modifications nothing only loaded Expo profile so that's our testing setup the rsxtreme I have an AIO mounted with a tiny bit of thermal paste and also just two screws so I can easily remove them and take off the AIO while it's running okay well that's quite a lot harder than I expected with what someone now unmount the AIO now checking the temperatures should increase quite quickly honestly that was more than I expected because we all know of the like 95 degrees Celsius limit on the AMD ryzen CPUs and for whatever reason like this was 20 more than usually I will investigate further I now adjusted the PBO temperature limit to 95 degrees Celsius I think that's the stock value it was set to Auto so I'm not quite sure let's see system is sitting back in Windows and I'm now going to remove the AIO again so still even with this limit why can this CPU get so hot on this board I flashed to a newer BIOS version previously it was f5a now it's f8 still very high CPU temperature that's possible just to double check the temperature values and where it like shuts down I'm double checking with this MSI Ace Port so I'm going to proceed to remove the AIO on the MSI board very interesting because it seems like we will see the same temperature region also way above like 95. until it shuts down I will now try this like brand new sealed 7600 non-x seems to be very similar with the 7600 non-x I mean personally I thought because AMD also lists 95 degrees Celsius as Max back I thought this would like throttle earlier or like shut down earlier but it seems to be the same kind of behavior at least both boards behaved exactly the same which is a good indicator that it's probably supposed to be this way I didn't check this before you probably also didn't like why would you take off a cooler to check the max temperature it reaches before it shuts down that's to really something you don't do but everything seems to be kind of normal so it's probably also not the board at least I mean checking with the RS extreme that means that we probably won't get any further from here it's still a very obscure case that the CPU can reach this kind of temperature to unsolder and kill itself Max thank you very much for providing this special CPU to us have fun with your new X 3D CPU I also enjoyed like looking into this and maybe analyzing some surfaces and stuff I hope you also got some maybe interesting insights and if you have a theory why this could have happened please let me know in the comments thanks for tuning in see you next time bye thank you

Channel: der8auer EN

Views: 105,004

Keywords:

Id: 34VbutE-Qss

Length: 16min 13sec (973 seconds)

Published: Sun Apr 02 2023

Reddit Comments

[u/COMPUTER1313]

If Der8auer sends that solder to a chemical analysis lab and confirms that the solder wasn't contaminated with something that made it melt at very low temps, I would be VERY curious of how the CPU reached 160C to melt the solder. Especially when the CPU owner claimed they didn't overclock other than using an EPXO profile.

Maybe a power/thermal circuit failure that lead to the CPU burning itself out? That would require opening up the die and running something like an electron microscope to compare that CPU's circuit to a known good one.

What is interesting is that the CPUs and boards he tested show that Zen 4 will happily run up to ~110C even if they were set with a 95C limit, before shutting down. Now if AMD claims that 110C region is safe for use, someone should ask Linus to build a passive boiling water loop (and a built-in tea/coffee maker) to cool the CPU at 105C for sustained usage just to see how long that CPU can run before failing.

[u/kyralfie]

Everyone is quick to propose theories of various places where AMD could've screwed up but, and I'm just saying, we can't deny the possibility of a failed delidding attempt from the owner - they could've applied too much heat, gave up, realized they borked the CPU but failed to admit their own mistake or simply connect the dots between it failing and their actions.

[u/Glissssy]

Oh shit, that testing does point to possibly malfunctioning thermal protection

[u/Kougar]

There's so many temp sensors in the die that a failure of one would not defeat a CPU's thermal protection in of itself. So let me posit a different theory.

This is a 7900X, so one of the CCDs has half the cores disabled. Could the hot spot that melted the solder have been in the fused off section? Whether that was from a problem with the fusing process not completing correctly or some other internal circuit issue that still shorted to active silicon elsewhere in the die? Or even a BGA short to the fused portion of the CCD underneath.

My thinking is if the overheating occurred in the "dead" part of the CCD then there wouldn't be any thermal protection or anything else, it would just run short and keep generating heat until it melted the solder and eventually damaged the rest of the die and/or solder connections.

[u/browncoat_girl]

The only way you're melting solder is if there's a short circuit and even then I'm highly skeptical the motherboard can put out nearly enough power to melt that much solder with a cooler on. My bet is a failed delidding attempt in a toaster.