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https://gmplib.org/gmp-zen5
連結內有一些CPU的圖跟兩台的配備
全部貼來PTT好像有點長，我截下面比較重要的部分+AI翻

We really don’t know what is wrong here. Let us list some observations and
thoughts:

The ambient temperature was in both cases quite low.
These are supposedly top-quality motherboard (We’ve had about 50 ASUS
motherboard over the years, and only had one failure).
The offset mounting does not look right to us. But this is how things are
supposed to be done.
It is possible that we caused the 2nd CPU failure by inadequate mounting of
the heat sink. It surely seems bizarre to have the thermal paste squeezed like
 shown on the pictures above!
But note that the 1st failure happened with a more centred heat sink. We only
made the off-centre mounting for the 2nd system as to minimise the risk of a
repeated system failure.
The so-called TDP of the Ryzen 9950X is 170W. The used heat sinks are
specified to dissipate 165W, so that seems tight. We have extra fans in the
cases and a low ambient temperature, making these 5W seem negligible. But of
course, this is not completely kosher.
We have a sister system for the 9950X, a 7950X which is similarly configured
and built. That system actually seems to run slightly hotter, but it has been
stable for a long time (under the same crazy load!).
The systems were under maximal load at the time their CPUs died, running very
tight handcrafted asm loops sustaining one MULX per cycle. That might be a “
hot” instruction.
Did the CPUs die of heat stroke? Modern CPUs measure their temperature and
clock down if they get too hot, don’t they?
We don’t overclock or overvolt or play other teen games with our hardware.
The extremely thin layer of thermal paste which resulted from the off-centre
heat sink mount, might seem fine. We however suspect that there might be a
problem, as when the system heats and cools, things bend a little. With a
remaining layer of thermal paste, such bending will not create any void as the
 paste’s elasticity will maintain some contact. When the thermal paste is
squeezed away as with the suggested Noctua mounting, an ever-so-slight void
between the CPU and the heat sink might be created.
Neither of the 9950X CPUs died immediately, instead they died the exact same
way after a couple of months at high load. This seems to suggest a gradual but
 predictable degradation.

我們真的不清楚問題出在哪裡。以下是一些我們的觀察與想法：

兩次故障發生時，環境溫度都相當低。
我們使用的是公認品質頂尖的主機板
（多年來我們用過約 50 張 ASUS 主機板，只壞過一張）。
偏置安裝看起來很奇怪，但這卻是官方建議的安裝方式。
第二次 CPU 故障有可能是我們安裝散熱器不當所致。散熱膏被擠壓成上圖那樣，確實有
點匪夷所思。
但值得注意的是，第一次故障時散熱器是置中安裝的。我們在第二套系統上改用偏置安裝
，正是為了避免重蹈覆轍。

我們有一套與 9950X 系統配置相近的 7950X 系統。那套系統的運作溫度似乎還稍微高一
些，但在同樣極端的負載下，它已經穩定運行了很長時間。
CPU 燒毀的當下，系統都處於滿載狀態，持續運行著我們手動編寫、極度精簡的 asm 迴
圈，每個時脈週期執行一次 MULX 指令。這或許是個發熱量極大的指令。
CPU 是因為過熱燒毀的嗎？現代 CPU 不是都有溫度監控，會在過熱時自動降頻保護嗎？
我們從不對硬體進行超頻、加壓或任何類似的胡亂設定。

兩顆 9950X CPU 都不是立即損壞，而是在高強度負載幾個月後，以完全相同的方式故障
。這似乎指向一種緩慢但可預測的漸進式損耗。


關於文中提到的off-centre mounting

We use a Noctua cooling solution for both systems. For the 1st system, we
mounted the heat sink centred. For the 2nd system, we followed Noctua’s
advice of mounting things offset towards what they claim to be the hotter side
 of the CPU. Below is a picture of the 2nd system without the heat sink which
shows that offset. Note the brackets and their pins, those pins are where the
heat sink’s pressure gets centred. Also note how the thermal paste has been
squeezed away from that part, but is quite thick towards the left.




----
因為天氣夠冷所以散熱用稍微不夠是可以的嗎?尤其是在大量數學計算上?
積熱應該還是會積在裡面吧?熱交換不夠快外面再涼也沒意義?
(編輯)
補充:看推文討論溫度可能不是主要原因

--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 1.160.16.3 (臺灣)
※ 作者: zseineo 2025-08-28 09:33:57
※ 文章代碼(AID): #1ehx88ND (PC_Shopping)
※ 文章網址: https://www.ptt.cc/bbs/PC_Shopping/M.1756344840.A.5CD.html

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