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heat from graphic cards

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ket View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ket Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jul 2017 at 7:22pm
Graphics cards heat up primarily in the VRM, GPU and vRAM areas. Heat naturally rises so there is some logic in a GPU being mounted "upside down" as any well placed side or front intake fan will be able to do a significantly better job of keeping a graphics card cool.

The problem you then have is any heat that is rising engulfs the CPU and VRM area of the mainboard. In a situation like this a air cooler for the CPU is a better choice than a AIO as it keeps the air flowing and moving which makes it easier for any top exhaust case fans to remove. Zen actually stays very cool assuming you aren't throwing over 1.3v through it with any good air or AIO cooler so heat is not a concern here, the mainboard VRMs are quite another story though.

You see, VRMs get got, extremely hot, when a CPU is under full load. There are thermodynamic solutions to this as well as VRM drivers which can help even further in spreading the thermal heat load by helping to make sure the VRMs have a more equal load. Combined with a good thermodynamic heatsink design and a heatpipe connecting the VRM heatsinks to further improve thermal load balancing it's possible to keep VRM temps relatively under control without the need of any extra fans.

Mounting a GPU "upside down" however would present a bigger problem to the VRMs so depending on the GPU a extra fan to aid the mainboard VRMs would be necessary which is likely why the idea of upside down GPU mounting fell out of favour quite quickly (yes it's been tried already). Thats the short story anyway, I could go in to a lot more detail but I'll leave it at that.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Codemang87 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Aug 2017 at 5:09am
I put an intake fan on the back of my case facing the VRM and it keeps my CPU abou 5 degrees cooler and the VRM about 8-10 degrees cooler at full load.  My GPU's are running stock but hardly get above 50C at full load. Before i added the intake fan the GPUs hit 60C and VRM idled at 60C.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote parsec Quote  Post ReplyReply Direct Link To This Post Posted: 15 Aug 2017 at 11:01am
Originally posted by terry2uk terry2uk wrote:

The hot side of a graphics card faces the CPU, and pushes the the heat towards the CPU? You lost me with that description.

how did i lose you , ststed the hot side of graphic card faces the cpu or central processing unit , and the fans under the card pushes the heat tpowards the cpu

The bottom of a video card mounted in a PCIe slot, which faces up towards the CPU, is the bottom of the card's circuit board. The circuit board has no ventilation openings in it, and may be covered by a metal back plate. That side may be a bit warm.

The vast majority of the heated air exhausted by its fan(s) is out through the sides of the card, for multiple fan type cards. Single fan "blower" type cards are mostly sealed around the sides, except for the rear exhaust.

Explain to me how video card fans push air up through a circuit board? The fans push the heated air out of the sides of the video card. We can see the heat sink fins though the open sides. The fans pull air into the card, through the heat sink fins, and out the sides of the card.

Yes, some heat is radiated by the bottom of the circuit board, but that amount is small compared to the heated air that is cooling the heat sink that is used to cool the GPU chip, VRM and memory chips.

In reality, the video card is a large heat source within a PC case. It radiates heat from all sides, except the actual "bottom" of the card where the fans are mounted. It actually can create more heat than a CPU does. Compare high end video card GPU chip's TDP spec to CPUs. A video card radiates most of its heat from the sides, and a little from the circuit board.

The real problem is a video card just dumps most of its heat into the PC case. Up, down, or sides does not matter, the heat is inside the PC case and will heat up anything else inside the case.

The next part of the problem is, PC cases with exhaust fans mounted on the top and top rear, pull the heat created by the video card up into the CPU and CPU VRM area. Heat rising is not a major factor when fans are moving air in a PC case. Only if the PC case was sealed and had no fans to move the air inside it, would heat rising be a factor.

Heat from a video card being pulled up into the CPU area is the first problem that proper PC case ventilation must address. Few if any PC cases are designed to properly remove the heat created by a video card. PC cases that have a side fan whose exhaust opening is near the level of a video card, with the fan mounted to pull air out of the case, is about the best we have.

I use a configuration that I found in another forum. Get a PC case with as many front intake fans as possible. I use the Fractal Define S, with three 140mm fans mounted in the front, all blowing air into the case. All of the unused PCIe slot covers on the back of the PC case are removed, to allow air to exhaust at the back. The IO panel metal shield is not used, all it does is block air flow out of the case. Add a side exhaust fan if you want to, otherwise leave it open for natural exhaust. No fans on the top of the case, except as intake fans. The top, rear exhaust fan can be used.
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