Thoughts on unorthodox GPU mount ? (et alia)

ioverclockers

ioverclockers

ioverclockers

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Hi, I finally decided to mod my Lian Li O11DXL with a front intake (see my other post). That makes me have (all fans are bequiet! silentwings 3 120mm pwm) 3 of them for intake and one of them for exhaust (2 will replace the 140mm Zalman CPU cooler).

Now I kinda gave up the idea of a vertical GPU mount. Basically, contrary to my initial thoughts (and the rationale of buying the Lian Li raiser kit), most tests I've seen conclude there's almost no difference in temps and that it's basically an esthetic issue, to "show off your graphics card"... :). I couldn't care less.

Now, i do intend to replace the stock heatsink with a morpheus II core one (that will drop the temps !), but would like to be able to have access to the remaining PCIe slots on the mobo (which I shan't have if I do a regular GPU installation in the 16x PCIe slot under the CPU heatsink).

So... i was wondering : why not simply clip the GPU (radeon VII) +morpheus on 2 or 3 120mm fans that I pin directly to the bottom (which is perforated anyway and has dust filters I could simply take out to improve the airflow) and use that as a direct exhaust ?

I'm aware that most people would use these fans for intake, in order to have the air getting directly to the pcb, but that would have the hot GPU air whirl up and get to the CPU before getting to the back exhaust...

Anyway, in my proposed configuration, the GPU would still get (some) fresh air from the 3 front fans anyway and as all hot air will be pulled down directly (I thought of 3 fans instead of 2 just so that the exhausted hot air can't get back in through the 'hole' that'd be left in the bottom) and can't get in the case nor the CPU in any way...

This would have course imply I need to buy a long enough PCIE4 raiser cable (if anyone knows of a good one, feel free to let me know), so it could still get over the other PCIe cards I would like to install...

The only drawback I see, is that the GPU isn't very much solidly attached to any frame that keeps it in place (just the two clips of the fans). So, maybe some sort of mounting rail or frame that'd allow for such a horizontal mount that I could fix to the bottom plate might be a good idea ? I simply don't know of any such beast on the market, so here again, if anyone knows of such a solution, please feel free to share it !

Personally I've only found these ones :
https://www.amazon.com/dp/B07Y43C9XD
https://www.amazon.com/dp/B07Y449XHG

Thanks for any feedback on all of this...

Here's a pick to make sense of it all :
https://imgshare.io/image/N5Yery
 
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If your motherboard has a second lower pcie slot at x8, just use that - unless you run certain compute workloads you won't see any difference in performance.

A pcie 4.0 x 4 would likely be fine as well as long as the Gpu supports pcie 4.0.

Having a cable from the first slot go over add in cards would be less than ideal.
 
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Well the signal has to travel a bit further and through sometimes questionable conductors, so in theory you could have speed issues (not working at full bandwidth etc..) or intermittent interference or drops due to not so great conductors but in reality i've not seen this manifest even with the chinese stuff from da bay.
 
I think you're overthinking it. Firstly, do you actually have plans to use other expansion slots? Most users simply don't use them for anything.

And if you DO use them, surely having a big riser cable floating around is going to be at least inconvenient, maybe even problematic?

I wouldn't recommend your planned graphics card mount as exhaust - it's not guaranteed to bring any airflow to the VRAM or MOSFETs on the PCB itself. YMMV but have a look at your cooler and PCB layout. It could work ok as intake - is there a reason you don't want to do that? Pushed air is more turbulent and should reach past the heatsink and towards the PCB - pulled air is smoother and takes path of least resistance e.g. around the PCB rather than over it.

In general though I also would suggest just using an 8x slot. I don't believe it should interfere with any other PCIe functions besides the 16x slot lanes but I suppose it'd help to know your motherboard model...
 
Hi thanks for the feedback.
LuckyBenski said:
Firstly, do you actually have plans to use other expansion slots?
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yes. For sure the 1x one for my wifi/bt card and probably another one for a PCIe=>usb one.
LuckyBenski said:
It could work ok as intake - is there a reason you don't want to do that?
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Primarily in order to avoid having the hot air whirl up to the CPU before exiting the case.
LuckyBenski said:
In general though I also would suggest just using an 8x slot.
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Why so ? Normally it's recommended to put the GPU in the 16x slot no, to give it max performance ?
LuckyBenski said:
I suppose it'd help to know your motherboard model...
Click to expand...
ASUS ROG Crosshair VIII Hero (wifi)

Extra question : would it be better to put 2x120mm fans underneath the GPU or rather 3x92 or 80mm fans in order to get maybe a better coverage of the GPU ? With the 120mm fans there could be some sort of "dead zone" in the middle, where the hotspot will be...
 
ioverclockers said:
Primarily in order to avoid having the hot air whirl up to the CPU before exiting the case.
Click to expand...
Ultimately most air cooled setups have the graphics card heat being dispersed into the case before exhaust. It's rare to see rear exhaust under a graphics card. Those setups normally do fine.

ioverclockers said:
Why so ? Normally it's recommended to put the GPU in the 16x slot no, to give it max performance ?
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Yes it is, but the performance difference is something like 1-3%. I used the lower slot in my setup to make hard tube routing easier for instance, never been an issue. Even top tier graphics cards don't saturate their PCIe connections.

I think that if you move to smaller fans you reintroduce the risk of warm air recirculating into your case around the edges. How wide is the Morpheus 2?
 
According to the mobo manual, this is the breakdown of the PCIe expansion slots:
3rd Gen AMD RyzenTM Processors
- 2 x PCIe 4.0 x16 SafeSlots (supports x16, x8/x8)
2nd Gen AMD RyzenTM Processors
- 2 x PCIe 3.0 x16 SafeSlots (supports x16, x8/x8)
2nd and 1st Gen AMD RyzenTM with RadeonTM Vega Graphics Processors
- 1 x PCIe 3.0 x16 SafeSlot (supports x8)
AMD X570 chipset
- 1 x PCIe 4.0 x16 (supports x4) - 1 x PCIe 4.0 x1
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So basically, does this mean that it doesn't matter in which of the x16 slots I plug the GPU ? I.e. that I'm going to get full x16 speed anyway, on condition that I don't plug any other PCIe card in one of those 3 slots ? If this is the case, I may indeed just plug it in the bottom one, freeing up the other PCIe slots. Thanks for confirming this.

If I do plug another PCIe card in one of the two x16 slots mentioned above, they both halve speeds to x8 each, right?
What happens if I
- plug the additional PCIe card in the AMD X570 chipset x16 slot ? Will that give me 2 full speed x16 PCIe devices ?
- plug the wifi/bt PCIe x1 card in the x1 AMD X570 chipset slot ? Will that somehow interfere with the speeds of the x16 slots ?
 
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The chipset connected x16 slot has x4 lanes. It's an x16 size socket with electrical connections for 4 PCIe lanes. So you won't get "full speed" from it but what are you planning to connect that requires more than x4?

In general the second x16 slot only has electrical connections for x8 lanes. So even if you only use the second slot it will likely run at x8 speed. Which is fine, as mentioned, a couple of % difference in performance. You can often see the pins stop halfway down the socket in photos.

It shouldn't interfere with anything to use the chipset x1 slot.

All this should be explained in the motherboard manual.
 
Well, not that much...
Other thing is that the PCIe connector is PCIe 3.0 only and that I wanted to be able to draw fully from the PCIe 4.0 possibilities of my mobo. This being said, it seems that that won't make a huge difference. If this is the case, I might revisit the vertical mount. Just afraid that the GPU+morpheus cooler+2 fans will be a bit too bulky for a vertical mount...
I'm trying to find out the shared connectivity between the PCIe slots and f.ex. my 2 M.2 slots and SATA ones in order not to loose too much potential...
 
Not sure I understand what you mean by "too bulky for vertical mount". I've only remoted mounted 1 GPU, but I have used mount supports on several GPUs. Some are 'L' shaped being attached to PCIe screw holes with arm running out below GPU fans so it sets on support to stop sagging.

asus_strix_4_non_reference_silver_4_gpu_support_bracket_mnpctech_gtx_980ti_ti_r9_390x_fa676783-030a-4cd6-9de5-2b6a671f16cf_480x480.jpg


7151hk-dIFL._AC_SX466_.jpg


I prefer the MNPCtech but upHere works well too. There are many others out there as well. Some use a brace from case bottom up to GPU.
images
 
doyll said:
Not sure I understand what you mean by "too bulky for vertical mount".
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What I meant is that the combination of the GPU with both the heatsink and fans will be quite space hungry :
RADEON VII
267 x 121 x 40 mm
MORPHEUS
254 x 98 x 44 mm
BEQUIET! SILENTWINGS 120mm
120x120x25
TBH, I don't know how modding the GPU with the morpheus will affect total diameter, but it'll certainly encroach into my bottom PCIe 16x slot and probably the PCIe 1x one just above...
Wasn't referring to sagging issues here.
 
You'd want those bottom fans to be intake wouldn't you? "Open air" coolers like on a Radeon VII and every other air cooled non "Blower" type cooler take air in through the fans, push it through the heatsink and dump it out the sides. With the GPU fans facing the exhaust fans, your GPU fans will not be getting very good airflow.
 
SonicSW20 said:
You'd want those bottom fans to be intake wouldn't you?
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yep.
I have modded the case to allow for frontal intake (3 fans) and one exhaust fan. There's parts of the case that allow for passive exhaust too. That should be enough.
The other option I was thinking about (cf. title of post) would be to simply place the whole horizontally on the bottom plate that allows for intake. That would require an extender cable but would allow for using the other PCIe slots on the mobo (this does mean I'd have the extender cable hanging over other PCIe cards, that's true...).
 
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