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Haswell PCI-E coldbug


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I've seen something similar with an early i7 940... but it was only one cpu at about the same temps Kenny describes...

I remember raisining a voltage insanely high to get past it but i have to get a bios screen in front of me to remember which one...


Many X58 boards had a sort of "QPI Degradation" to them, but it was unrelated to temperature. As QPI approached 4GHz (BCLK at 220), the QPI (link between X58 Chipset (which handles PCI-E lanes) and CPU) would stutter really badly and cut 3D frames massively. This is why QPI Slow Mode was useful for 2D but not for 3D.


I uploaded this a few years ago while messing with my RIIIE:


Edited by xxbassplayerxx
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Capacitor capacitance goes down with temperature, it's possible that the little 0.1µF coupling caps drop enough that the signals don't last long enough to transfer.

If they're on the board for Haswell you could try replacing them and see what happens :D

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Fyi, we had a funky cold issue with Z87 last weekend.


At -135°C, 01 Nature was ~70FPS; at -107°C, 01 nature was ~ 220FPS. Reboot solved the issue though.


PCI-E link 'cold slow' .. strange.. sometimes I get it.. other times not. Could be tied to input voltage ratio's. I have had both: VGA signal 'drop' to black screen, and VGA/PCI-E cold slow.. but adjusted Input and IO's and have not had it return.. yet

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