Troubleshooting Multiple gpu setups that use Riser cards

Ian&Steve C.
Ian&Steve C.
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Brandon Clark wrote: That

Brandon Clark wrote:

That makes me wonder if power supply problems are a source for a lot of the instability we hear about with risers. Just because we can install a one-to-four PCIe splitter on a motherboard slot it doesn't mean that particular slot has the watts available to meet the needs of that many cards . . . . One one motherboard I have the slots intended for graphics cards are rated at 225 watts, while the ones for general usage are only rated at 25 watts.

Another riser question: With one of my systems the board has two PCIe x16 slots that are already intended for graphics cards. I want to go to risers for better cooling though. Would the ribbon style risers that take up the full x16 length be the better option for those kinds of slots, since all I am doing is relocating a single card?

Then, to add other cards I could use the USB style risers that only take up an x1 slot?

Thanks

when using the USB based riser, no power is supplied from the PCIe slot at all. zero. only the data connections are carried via the USB cable. power is supplied to the GPU's slot via power input directly from the PSU (usually in the form of a Molex/SATA power connection, or more ideally a 6-pin PCIe cable connection). so the power rating of the slot makes no difference in this case.

 

this should make things easier to understand:

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Brandon Clark
Brandon Clark
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That makes sense - the

That makes sense - the external power connector supplies the PCIe riser board as though the riser was a part of the main MB. If the card has its own power connector then the PSU would be connected to the card directly as well.

Another question: does anyone have experience with mini PCIe to PCIe adapters? I'm thinking of something like this one. Could one of these be used to convert a mini PCIe slot to something where a graphics card (via USB riser) could be installed?

What has me wondering is that I have about ten small Dell Optiplex mini PCs that do not have PCIe slots for graphics cards. (They were my first salvaged BOINC hardware.) I have been considering retiring them now that I have more capable hardware. But if I could use the adapters above to add a small GPU to each then that might be a good way to cheaply add more capability to my systems. Does anyone know if that would work?

Thanks,

Tom M
Tom M
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Brandon Clark wrote: Does

Brandon Clark wrote:

 Does anyone know if that would work?

Thanks,

While I don't know it will work, only the bios not supporting it would keep it from working AFAIK.

Tom M

Over the hill?  What hill?  I don't REMEMBER any hill...
A Proud member of the O.F.A. (I've forgotten what that stands for.... ;)

 

 

 

 

Brandon Clark
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I ordered a few mini PCIe to

I ordered a few mini PCIe to PCIe adapters for a few bucks, and also ordered some riser cards to go with them. When they come in I'll try them out and report back on the results.

Tom M
Tom M
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I have a "new"

I have a "new" question.

When you start running a lot of Video cards on say a 1600 Watt PSU (EVEA) you need to distribute the power draws as widely as you can.

Each riser card base probably needs to have up to 75 watts available for it to replicate the standard PCIe slot on an MB.

According to Tom's Hardware, my Rx 5700's should be drawing around 171 watts for the total card.  They did a hardware-sensor-based test.

It looks like each SATA jack is supposed to be rated at about 77 watts (Google Article).

So "in theory" each SATA Peripheral cable should be able to handle up to 4 Riser card bases?

I just got done separating two Rx 5700 cards onto separate SATA cables because both work but not on a single SATA cable (apparently).

The other SATA cable is currently driving 3 Rx 5700's with no apparent trouble.

Does thing imply that at least one of my SATA cables is damaged?

Short of using a PSU adapter to hang a 2nd PSU on my mining rig how else should I be trying to balance the power loads and cables?

It is probable I will be hanging a 7th Rx 5700 GPU on this rig.

Tom M

 

 

 

 

 

Over the hill?  What hill?  I don't REMEMBER any hill...
A Proud member of the O.F.A. (I've forgotten what that stands for.... ;)

 

 

 

 

Ian&Steve C.
Ian&Steve C.
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Tom M wrote: I have a "new"

Tom M wrote:

I have a "new" question.

When you start running a lot of Video cards on say a 1600 Watt PSU (EVEA) you need to distribute the power draws as widely as you can.

Each riser card base probably needs to have up to 75 watts available for it to replicate the standard PCIe slot on an MB.

According to Tom's Hardware, my Rx 5700's should be drawing around 171 watts for the total card.  They did a hardware-sensor-based test.

It looks like each SATA jack is supposed to be rated at about 77 watts (Google Article).

So "in theory" each SATA Peripheral cable should be able to handle up to 4 Riser card bases?

I just got done separating two Rx 5700 cards onto separate SATA cables because both work but not on a single SATA cable (apparently).

The other SATA cable is currently driving 3 Rx 5700's with no apparent trouble.

Does thing imply that at least one of my SATA cables is damaged?

Short of using a PSU adapter to hang a 2nd PSU on my mining rig how else should I be trying to balance the power loads and cables?

It is probable I will be hanging a 7th Rx 5700 GPU on this rig.

Tom M

 

 

 

 

 

 

stop using SATA cables. You’re going to start a fire.
 

Use only the 6-pin adapters, or use 2x SATA connectors or 2x Molex connectors feeding a 6-pin connector per riser. 
 

the “77w” rating you found for a SATA connector (if true) is likely the sum of the 12v, 5v, and 3.3V lines that are present on the connector. But you’re not using all of those. You’re only using the 12V line for your risers. And each SATA connector only has one(1) 12v line. A 4xSATA peripheral cable is basically taking that one line and splitting it up to power 4 devices, like 4 HDDs or 4 SSDs which don’t use much power.
 

DO NOT use them to power four GPU risers! From what I’ve found, SATA spec is 54W for the 12V line. 
 

I would recommend getting a second PSU so you have enough connectors.

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Keith Myers
Keith Myers
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Absolutely what Ian states. 

Absolutely what Ian states.  Max 54W from a single SATA cable.  You can only drive one high powered device with a single SATA cable.

And I am not talking about the multiple SATA daisy chain connectors on the cable.

One physical cable from the power supply per one device.

 

Tom M
Tom M
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Ian&Steve C. wrote: Tom M

Ian&Steve C. wrote:

Tom M wrote:

I have a "new" question.

When you start running a lot of Video cards on say a 1600 Watt PSU (EVEA) you need to distribute the power draws as widely as you can.

stop using SATA cables. You’re going to start a fire.

Since I haven't had a fire "yet" using the SATA cables I have that feed into 6 pin adapters I have switched all SATA cables I have driving gpus to single cards.

The rest are being driven by Pcie cables.  I have more SATA cables on order because I robbed one PSU to get enough for the other.

If I can get them reorganized to the Pcie spilt cables are all driving two riser cards I may be able to (eventually ) support a 7th Rx 5700 once I get it.

Tom M

 

Over the hill?  What hill?  I don't REMEMBER any hill...
A Proud member of the O.F.A. (I've forgotten what that stands for.... ;)

 

 

 

 

Ian&Steve C.
Ian&Steve C.
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Tom M wrote:Since I haven't

Tom M wrote:

Since I haven't had a fire "yet"

famous last words. lol.

 

I've been down this road. I've made this mistake. You might get away with it for a while, but eventually the heat generated from pulling such high current over such cheap cables (those adapters SATA-PCIe adapters are chinese garbage, they take a SINGLE 12v lead and just split it to two pins on the PCIe connector) eventually you're going to melt a connector at best, or start a fire at worst.

Like I said, I've done this. it ran "fine" for some months, until while troubleshooting i discovered one of the connectors was melting. I never went back to this setup after that. that was when I was mining with 8x RX570s (before I really started getting into BOINC, I sold these off for nvidia cards back in like 2018).

If you're dead set on using these SATA leads, run only a max of two risers per peripheral cable from the PSU and get yourself some SATA or Molex adapters that use TWO connectors per ONE PCIe (like this: 2xSATA to PCIe).

I'm still highly recommending that you do it the right way though and get a second PSU for more PCIe connectors. You'll thank yourself later.

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Ian&Steve C.
Ian&Steve C.
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Fitting that this post hit my

Fitting that this post hit my Reddit dashboard today. 
 

Friendly reminder to stop using sata to power risers

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