D630 temperatures / heatsink concerns

Hi all,

My D630's motherboard died recently, so I installed a used replacement, along with a used T9300 processor. The system is now running again, and all seems fine, except for temperature readings (by i8kfangui and HWMonitor) that seem odd in some respects:

- Idle: CPU temperatures are low, but there's a significant difference between the two CPU cores (e.g. 33 and 40 degrees when I had it idle a few minutes ago)

- Load: CPU temperatures climb very high after a few minutes of Prime95 (e.g. 96 and 87 degrees when I tested just then)

Is this unusual behaviour, and if so, is it likely that I haven't re-installed the heatsink correctly?

By comparison, my second D630 (with a T7700 processor) is hotter when idle, but the difference between the two cores is generally only 0-2 degrees. Under load (Prime95), the temps do reach 90 during some parts of the test, but take longer to get there, and are much lower for the most part (generally hovering at the low to mid 70s).

Other details that may be relevant:

- I did not have replacement thermal pads, so cleaned the old ones off and used Arctic Silver 5 (following instructions from the Arctic Silver website). Perhaps I didn't use enough?

- The replacement board is Intel based, whereas the old one was nVidia based. Should I purchase an Intel-specific heatsink? (I've read of people using the nVidia one on an Intel board with no problem, so I've left the GPU 'arm' floating above the GPU without making contact. GPU temps seem fine.)

- I placed a copper shim between the northbridge and and heatsink, to compensate for the lack of a thick thermal pad. However, the shim does not seem as thick as the original pad, and can be moved around by hand with a bit of pushing. Chipset temps seem fine, but maybe the placement of the overall assembly is slightly unbalanced as a result of the thickness of this part not being correct?

Any advice/suggestions would be appreciated. Thanks!

 

It's not unusual for there to be a significant difference in temps between the two cores, but 7C does seem to be a lot...

My guess is that you either repasted it funny or that the shim you're using is tipping the heatsink such that it isn't properly contacting the CPU die.

In general there shouldn't be an issue with using the Nvidia heatsink on an Intel board. The GPU arm floats over the SB, not the GPU, though. In the Intel motherboard, the GPU is integrated into the chipset.

 

Thanks for the quick response.

I agree with your suggestion that it may be 'tipping' due to the incorrect shim thickness. Looks like I'll be dis/re-assembling it again soon (sigh).

Thanks, I hadn't realised this. I just assumed it was the GPU due to it being located where the nVidia chip would otherwise be. Now I understand why it's so slim and does not require cooling.

 

Does anyone know the correct thickness for a shim (or thermal pad) to place between the northbridge and the heatsink? I think the one I'm currently using is about 0.9-1.0mm.

Also, is it better to actually attach the shim to the heatsink (e.g. with a thermal adhesive), or to just use thermal compound on both sides of the shim and screw the heatsink in tightly?

Thanks again.

 

Hi again,

Not sure if there's much interest in this topic, but I'll provide an update anyway, in case someone else eventually experiences a similar situation.

I decided to remove the assembly and permanently attach the shim to the heatsink using some Arctic Silver thermal adhesive. While doing this, I also cleaned everything, re-applied the (non-adhesive) Arctic Silver to the CPU and chipset, and made sure everything was screwed in as tightly as possible.

Unfortunately, it hasn't lessened the difference between the two cores; there's still 5-10 degrees C difference between them at all times.

However, load temperatures seem to have improved somewhat: instead of climbing to the high 80s / 90s after less than 5 minutes of Prime95, the CPU temps peaked at 79 C, and did not go beyond this at any point during nearly 30 minutes of Prime95.

Admittedly, this is not a particularly thorough test, and other factors such as ambient temperature differences could be at play. But it seems reasonable to conclude that at the very least, I haven't made things worse.

The 'imprint' in the old thermal paste looked quite uneven, so as expected, it seems the heatsink simply wasn't (and still isn't) making an even enough contact with the CPU.

I guess the next thing to try would be replacing the heatsink with the correct Intel (not nVidia) type? But is there any point, if the system is stable and the temps don't get too high?

 

Why are you using a shim? Remove it and move the thermal pad from the GPU arm to the northbridge. It'll be enough cooling for the chipset.

BTW...gap distance varies a lot depending on how the heatsink arm is bent. If you use something solid, it may exert too much pressure on the component, or it will tilt the heatsink. That's why you need to use something soft like a thermal pad.

 

Thanks for the input, Robin. What you have written makes sense, and I will look for replacement thermal pads to try.

Any idea what thickness to use (assuming I can't find an official replacement)?

I'm using the shim because I removed the pads, thinking they were not designed to be re-used. So the shim is to help fill the gap left due to not having a pad. Also, I'd read about people successfully using shims to improve the cooling on their heat-prone nVidia-based D630s, so I assumed I could do the same on an Intel version (even though the cooling improvement is not required).

However, I don't have the tools or know-how to precisely determine which shim size to use, so perhaps the pad approach would be a better option for me.

 

I wasn't able to find any OEM pads (note that DP/N UP755 will not work, it's actually a thin layer of grease), but any quality thermal pad should be fine.

I have a spare new DT785 heatsink from Dell, and the pad is approximately 1/16", which would be 1.5mm.

 

Thanks. That pad is only for the chipset/GPU, right? Will thermal compound suffice for the CPU, or should I use some kind of pad on that, too?

 

You should use Arctic Silver 5 for the CPU.