Full length PCIe cards in a half length slot

[ellisif]

This may be a stupid question, but on some server motherboards, only about half of a PCIe slot is present. There are 8x data lanes, but does the lack of the rest of the pins present any sort of power delivery issue or other issues to a card that is full length 16x but placed in these half length 8x slots? 

 

For example, on this Tyan S7012 motherboard, all 5 of the slots are 8x but only half length. Would a normal graphics card work in these?

[MrJoosh]

3 minutes ago, ellisif said:

This may be a stupid question, but on some server motherboards, only about half of a PCIe slot is present. There are 8x data lanes, but does the lack of the rest of the pins present any sort of power delivery issue or other issues to a card that is full length 16x but placed in these half length 8x slots? 

 

For example, on this Tyan S7012 motherboard, all 5 of the slots are 8x but only half length. Would a normal graphics card work in these?

AFAIK, 16x cards will work in an 8x slot, but only at a max of 8x bandwidth. IIRC the extra length on the connection is purely to handle the data transfer of the additional 8 lanes. I think you have to cut out the slot to allow the card to fit in though...

 

Other people may be along soon who are more qualified to comment though, so I'd believe them over me 

[Damascus]

A gpu that runs on pcie x8 would fit, they do exist.  Other than that I doubt it.

[minibois]

The first left side of the port (the smaller section, when talking about 16x slot/full sized slot for example) is the power, the rest of the port is data. So putting a 16X product in an 8X or even 4X slot only means you are providing less data to it.

[Damascus]

Just now, MrJoosh said:

AFAIK, 16x cards will work in an 8x slot, but only at a max of 8x bandwidth. IIRC the extra length on the connection is purely to handle the data transfer of the additional 8 lanes. I think you have to cut out the slot to allow the card to fit in though...

 

Other people may be along soon who are more qualified to comment though, so I'd believe them over me 

The slot is physically restricted to 8x

[rn8686]

It looks like the side of the slot is open, it should still physically fit (It will just run at x8 instead of x16). 

[ellisif]

 

Just now, MrJoosh said:

AFAIK, 16x cards will work in an 8x slot, but only at a max of 8x bandwidth. IIRC the extra length on the connection is purely to handle the data transfer of the additional 8 lanes. I think you have to cut out the slot to allow the card to fit in though...

 

Other people may be along soon who are more qualified to comment though, so I'd believe them over me 

Just now, Damascus said:

The slot is physically restricted to 8x

Most of the dual LGA 1366 motherboards with 8x length slots are actually already pre-cut to allow 16x cards it seems, I am mostly just afraid of power delivery issues for cards that need both board and external power (e.g., a GPU) rather than data issues. 

 

2 minutes ago, Minibois said:

The first left side of the port (the smaller section, when talking about 16x for example) is the power, the rest of the port is data. So putting a 16X product in an 8X or even 4X slot only means you are providing less data to it.

Thanks, I didn't know that about the first part being power delivery. That clears most of it up for me.

[ellisif]

Just now, huilun02 said:

Hopefully its PCIE 3.0 otherwise its going to bottleneck a powerful gpu

You won't get any mobo power delivery issues

Well, there's no point in putting a powerful GPU on such old motherboards (the ones I'm looking into, anyways), I just might throw some random hand-me-down GPU so it has more than the utterly garbage IGPU on most of them. 

[tt2468]

7 hours ago, huilun02 said:

Hopefully its PCIE 3.0 otherwise its going to bottleneck a powerful gpu

You won't get any mobo power delivery issues

It will not bottleneck the GPU at all. PCIe 2.0 vs 3.0 on GPUs actually doesn't make a noticeable difference.

 

You can run a GPU in an x8 slot, but it has to get power from an external source (6+2 pin PCIe)

Many server motherboards don't actually support the full power delivery, because servers aren't generally meant for GPUs. Lots of server motherboards only supply 75w of power. Just keep that in mind.

[i_am_kingjonny]

Didn't read any of the other replies, but figured I'd give my experience. I have ML370 G5 with 8x slots running at 4x. Took a dremel to the graphics card (HD7770) and chopped off half the slot but it still didn't work. Turned out I needed a bus expander which took the bandwidth from the neighbouring slot to make up the speed on the 8x to full 8x. Needed to use an extension ribbon to get under the card but works out ok floating in the realms of the case. No detectable signs of decreased performance, but OCing has been a pain to the point I just didn't bother. Got 127% increase for a fair while (55celcius under load) but now it gets confused. Maybe I cooked it. Anyway, definitely doable, but make sure you don't chop off too many pins!!

[samiscool51]

it works, but the card will operate in 8x mode and run at that speed

also some cards and MB's will refuse to work if they are in this config,

be careful some people have permanently broken their equipment by doing this

[necro1999]

yes to the 16x pcie cards. the thing to look out for is what the card hits on the motherboard. pny gt 730 is a 8x and is to short to hit anything. Just dont expect great gaming.

[Jarsky]

If the card has external power source (PCI-E or Molex power) then you just need an 8x to 16x PCI-E riser so you preferably arent chopping up the board.

You can find them on eBay or Alibaba easily. 

 

[Pyroven]

Hey did you ever buy/build this? I have the same motherboard and am having issues with running a GPU.

[Pyroven]

On 24/05/2017 at 2:39 AM, samiscool51 said:

it works, but the card will operate in 8x mode and run at that speed

also some cards and MB's will refuse to work if they are in this config,

be careful some people have permanently broken their equipment by doing this

How would doing this permanently damage the parts? I'm having issues running this set up myself and trying to work out what's wrong with it.

[Pyroven]

On 19/05/2017 at 10:11 PM, tt2468 said:

It will not bottleneck the GPU at all. PCIe 2.0 vs 3.0 on GPUs actually doesn't make a noticeable difference.

 

You can run a GPU in an x8 slot, but it has to get power from an external source (6+2 pin PCIe)

Many server motherboards don't actually support the full power delivery, because servers aren't generally meant for GPUs. Lots of server motherboards only supply 75w of power. Just keep that in mind.

How would one find out whether a motherboard supplies enough power through it's PCIe slots? I have  tyan S7012 and an R9 280 which might be having power issues.