GPU running cooler in a lower PCIE slot?!

Daaaveee

Daaaveee

Daaaveee

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This evening I was changing my CPU overclock, trying lower volts, offsets and seeing if I could get 4.7ghz under 1.4v (spoilers, my CPU is happier at 4.6ghz!)

Anyway, I thought I would drop the GPU down to the next slot in my Gigabyte Z170MX-Gaming 5 for a while to give me easier access to the CMOS battery to reset. After finishing with the CPU tests I fired up BF1 and had a couple of hours gaming.

Now heres the interesting part, my GPU temps were around 3-4c cooler than normal! Same 21c room temp as normal, same CPU overclock and voltage as before, and same +100mhz overclock on the GPU with no extra power or volts.

Settling at 2025mhz my MSI GTX1070 Gaming X was sitting at around 74-75c in the top slot, but in the lower slot it was at 71-72c. As the pictured below its quite close to the PSU which I would expect to hinder cooling.

I am running the PSU fan up as the case it sat on carpet so I didn't want to suffocate it, so the GPU has more open space below it. That being said I have never seen the fan spin even under heavy load so the PSU isn't breaking a sweat at all.

In the top slot the GPU is pretty close to the CPU cooler, and anecdotally when just feeling the air around the GPU it is much warmer on the top side behind the backplate, compared to the fan side. I am assuming that the extra air space is allowing the heat to dissipate more quickly and therefore leading to a few degrees less on the core?!

Anyway thought I would share this 'cool story bro', if anyone else finds it interesting or has found similar results, or results the other way!

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I am running the PSU fan up
so all the hot air from gpu is being sucked through the psu, not worth it for a 2deg decrease in temp.
74 is fine for a gpu, if it was a drop from say 85 to 75 then it would be worth it
 
The PSU fan still doesn't spin even with the GPU so close and under full load so it's not going to be bothering it very much?

I see what you mean, it's only a couple degrees.
 
Daaaveee said:
The PSU fan still doesn't spin even with the GPU so close and under full load so it's not going to be bothering it very much?

I see what you mean, it's only a couple degrees.
Click to expand...

If the psu fan isn't spinning (good news) the temp drop will be down to better airflow over the gpu backplate
 
Definitely seems that way, I didn't realise airflow over the backplate would make any difference, but it makes sense that this would be the hotter side and therefore would benefit more :)
 
Your GPU is only running at pci-e 3.0 8x in that slot. According to Gigabytes website only the top slot is 16x. I would not be running the GPU that close to the PSU either. Probably the reason your PSU fan isn't spinning up is because the GPU fans are sucking the air out of the psu. This would mean that the psu has it's airflow reversed so it's coming in through the rear grill and up through the fan grill. Stick a bit of wood under the case and run the psu fan down.
 
I wonder if 8x would make the GPU run a little cooler too? Will run a few benchmarks to see how much it's effecting performance compared to 16x.

The PSU never span up with the card in the top slot anyway, will see later if the GPU is pushing air through it or pulling it out.
 
Probably a combination of reason for GPU running cooler. Lower speed PCIe socket, open PCIe back slots letting heated air from GPU exit case easier are first things I think of.

Your PSU is too close to GPU (as others said above). What may be happeing is the PSU airflow is moving backwards from back of case through PSU and up into GPU cooler.

I would turn the PSU over and set some 30-50mm blocks under each of the case feet to raise / space it up off of the floor. Really, I would make a open framed base with 30mm or 40mm castors
 
PSU fan still doesn't spin up at all (apart from boot fan check) the only airflow was a slight warm breeze out the back of the PSU.

Ran a few benchmarks on 8x slot and then back up in the 16x slot and they were all +- a few points or frames, more or less within the margin for error.

Back up in the top slot now anyway and definitely a couple of degrees warmer up there, but still mid 70s when overclocked, nice a quiet too so all good.

Will look in to sitting the case on something solid or some casters and flipping the PSU back over, although the RMx750 is a great unit and under no stress running my system so it's not much of a worry :)
 
Oh and doyll I run without any pcie slot covers based on your others posts I've read :) I definitely think the 2 free above it were helping airflow across the backplate
 
As long a GPU is in upper slot PSU orientation is not an issue.

Thanks for update and conformation of better airflow without PCIe slot covers.
FYI, easy way to check direction of airflow is with a incense stick, cigarette, match flame, etc. If there is even the slightest bit of air movement they usually pick it up ;)
 
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