Why are the heatsinks and fans on the bottom?

J

jusluv2play

Limp Gawd
Joined
Dec 13, 2004
Messages
130
Been building PC's for a few years now and have lately began to wonder this.

Why did the videocard engineers/ designers put the heatsink and fans and other hardware on the bottom of the videocard?

My answer would be that in the early designs, heat dispersion wasn't really an issue so they left it like it is.

But in todays systems, heat is a major issue we all know. And we all know that heat rises, therefore it has a more difficult time getting up and around the larger cards these days.

Wouldn't it make sense to have the heatsink and fan on top to allow the air to exit the pc closer to the powersupply area? I know the BTX format is supposed to really help maximise air flow, but that spec is still quite awhile away.

This may be a ridiculous question, buy I've asked a few local PC friends and they really didn't understand it either after they thought about it.

Opinions?
 
think it relates to the original "desktop" design, that is mobo's were normally horizontally based, therefore, air didn't come in from the bottom so much as it just came from the side.
 
hmmm, good question. i actually thought about that a few times whilst putting my pc together. they definitly should change that, cooling could be a hell of a lot more efficient that way because when the heatsink tries to cool the system, the hot air just rises back into the card, so, in theory, if they changed the design, the heat would dissipate more efficiently up through the air.
 
i agree on the desktop design,


and would you want ur video card pumping all that excess heat directly in the area of ur processor?
 
The AT standard had the components on add-on card facing upwards, then came along ATX (damn you, intel), the idea being that the power supply would suck air in and blow it over the CPU heatsink (like THAT would have worked for long :rolleyes: ), and to keep dust off the components.

It was a dumb decision but thankfully it will be corrected with BTX.
 
The reason is because there are high limitations for the cards, the top has a pretty low clearance where as the bottom has a much greater clearance. Each card has to conform to this or it won't be an ISO specification card and might not fit in certain circumstances.

Also, the Graphics card doesn't have to be at the "top" of all the other cards as that is not in the ISO specification so the cards still have to conform to to having only a certain clearance on the top of the card.
 
ISA video cards face up :p

I think this standard was originally set near the end of the ISA era. PCI cards needed to be distinct so they simply 'flipped' the card over. This set a new layout, without needing to change the AT case standard since the holes at the back still line up..

@MetalStorm
I don't think it's a clearance issue. Whether the card was facing up or down, it still has to line up with the hole at the back of the case so the thickness should be the same. Compare an ISA card to a PCI/AGP card, if you see the layout, you'll note that 'clearance' doesn't really matter.

EDIT: I seem to be the only one who remembers the ISA standard. Man, i feel old :rolleyes:
 
Sly said:
ISA video cards face up :p

EDIT: I seem to be the only one who remembers the ISA standard. Man, i feel old :rolleyes:
Click to expand...

i remember the ISA days, and even using MFM drives. I also remember IRQ conflict hell...glad thats nearly gone.
 
Me too on the ISA and IRQ issues! I remember fighting with a damn Winmodem over IRQ conflicts for days! I wanted my newfangled Internet I paid so much for 10 years ago. I feel the age bug too. :D
 
For reference:

ISA
mdacarda9zu.jpg


PCI
u18796ex.jpg


As you can see, in terms of space, there really isn't much difference between the two. So decision to flip the card may be more of an aesthic rather than a technical one.


and a bit of trivia for the newbies. Before they were cards, they were referred to as 'adaptors'. Video adaptors, sound adaptors, joystick adaptors, etc. Any kind of multifunction adapters were rare. You have a foot long card just for the parallel port, another foot long card for the Hercules, etc. The one above with two ports was pretty rare until near the end of ISA.
 
why cant they manufacture the core on the other side of the card is my question...but nvm migh be northbridge issues
 
Sly said:
and a bit of trivia for the newbies. Before they were cards, they were referred to as 'adaptors'. Video adaptors, sound adaptors, joystick adaptors, etc. Any kind of multifunction adapters were rare. You have a foot long card just for the parallel port, another foot long card for the Hercules, etc. The one above with two ports was pretty rare.
Click to expand...

Honestly, i've called them cards since the ISA days. The terms have always been interchangeable, with "card" being more of a slang term. "adapter" is the more technical term. Modern day video cards are still called adapters. Take a look at your Windows device manager, and your video card will be under the category "Display adapters"
 
Just about every draft of the BTX standard I've seen has the motherboard mounted on the left side of the case, as opposed to the right side with current ATX. This means that standard AGP / PCI will now be mounted upside down in BTX relitive to ATX. Thus the GPUs and heatsinks will now be on top.

You can still do this now if you want to... no one said you couldn't mount the HD's and CD/DVD drives upside down in your case, and then flip your case over.
 
I would think it''s smarter that it's down not up due to the cooler temperatures at the bottom of the case and the hotter aire rising ...

the cold air would enter the case go to the bottom and then be used to cool the cpu and then rise to the top of the case and then exit.

If it was the other way around I would think that it would be a lot harder for the video card to get cooler

Just my thoughts
 
Ballz2TheWallz said:
why cant they manufacture the core on the other side of the card is my question...but nvm migh be northbridge issues
Click to expand...

The X850 XT-PE and 6800 Ultra HSF's might bump into the chipset or CPU. Also when BTX fixes this issue by having the motherboard on the other side of the case, you would be unfixing what you have just fixed.
 
They put the heatsink/fan on the bottom because the GPU and RAM modules are on the bottom. As to why you buy the cool card coolers, then face them downward, who knows? Could be to keep the heat dissipated by the vid card from mixing with the CPU fan's air, causing turbulence, which makes the air sit still, defeating the purpose of both fans.
 
Remember when VLB came out and we were all EWW COOL and we all went out and got the Diamond Viper to play Doom?

ISA->EISA->VLB Then PCI came out and flipped it, and all the heat sinks were upside down. Actually, before VLB, a heatsink was CPU only, and what was a fan for?

I remember back in 9th grade (and Im not that old) when 486DX2 80 was the shizznit, my friend and I calculated how much 1GB of RAM would cost. It was 48,000 dollars then... all of in 8Mb SIMMS 32Pin. Hehe those were the days of who had the most effective autoexec.bat and config.sys files. And we didnt have non-flammable pajamas back then either!
 
One of my cases has the CPU on the bottom and the cards facing up. It also has the PSU fan right over the CPU. But I don't really think that is was set up for airflow, more for compactness. The case is literally only a little bit taller than a ATX mobo and the drives block access to the bottom (well, top in this case) PCI slots. Haven't really noticed any cooling benefit for video in it.
 
Jicks said:
Honestly, i've called them cards since the ISA days. The terms have always been interchangeable, with "card" being more of a slang term. "adapter" is the more technical term. Modern day video cards are still called adapters. Take a look at your Windows device manager, and your video card will be under the category "Display adapters"
Click to expand...

I guess. Everyone i knew (and the adults who introduced me) referred to them as adaptors. We didn't start using the term 'cards' until later. Maybe because all we had to go on were the technical manuals?

Imagine a 10 year old reading computer manuals instead of picturebooks in the late80's-early90's. Was anybody else here like that? :D Raise your hands proudly and scream "I AM A NERD!!!"
 
Sly said:
ISA video cards face up :p

I think this standard was originally set near the end of the ISA era. PCI cards needed to be distinct so they simply 'flipped' the card over. This set a new layout, without needing to change the AT case standard since the holes at the back still line up..

@MetalStorm
I don't think it's a clearance issue. Whether the card was facing up or down, it still has to line up with the hole at the back of the case so the thickness should be the same. Compare an ISA card to a PCI/AGP card, if you see the layout, you'll note that 'clearance' doesn't really matter.

EDIT: I seem to be the only one who remembers the ISA standard. Man, i feel old :rolleyes:
Click to expand...

I still have a VESA bus vidoe card lying around. Now THOSE were the days (laugh)
 
Sly said:
I guess. Everyone i knew (and the adults who introduced me) referred to them as adaptors. We didn't start using the term 'cards' until later. Maybe because all we had to go on were the technical manuals?

Imagine a 10 year old reading computer manuals instead of picturebooks in the late80's-early90's. Was anybody else here like that? :D Raise your hands proudly and scream "I AM A NERD!!!"
Click to expand...

well it was 1981 for me, got an Atari 400. My dad was cool and bought every manual they made. I still have the Asembly Listing (w/comments!!) for the Original OS. 12 years old and mucking around with assembly...how scary is that?
 
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