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Can I put an x8 RAID controller into an x16 PCIe slot?

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July 5, 2014 9:35:02 PM

I have an Intel DX58so motherboard that I'm trying to utilize as a file server.
I pulled a Dell RAID controller out of an old PowerEdge server. It appears to be an x8 card because it is about half the length of an x16 video card but has too many edge connections to be an x4. If I put it into an x4 slot, some of the pins hang in space.
However, the LSI specs say that it is a 4x card.
Either way, wouldn't you expect it to work in a 16x slot? It fits nicely, but when I power up the system turns itself off within 2 seconds.

What am I doing wrong?
This motherboard has 6 internal SATA connectors that can be configured for RAID. I'm thinking the hardware on the Dell card will out-perform the SATA controller on the motherboard.
Am I right, or would I be better off to use the integrated controller from Intel?

a c 169 V Motherboard
July 5, 2014 9:50:24 PM

thewiley1 said:
I have an Intel DX58so motherboard that I'm trying to utilize as a file server.
I pulled a Dell RAID controller out of an old PowerEdge server. It appears to be an x8 card because it is about half the length of an x16 video card but has too many edge connections to be an x4. If I put it into an x4 slot, some of the pins hang in space.
However, the LSI specs say that it is a 4x card.
Either way, wouldn't you expect it to work in a 16x slot? It fits nicely, but when I power up the system turns itself off within 2 seconds.

What am I doing wrong?
This motherboard has 6 internal SATA connectors that can be configured for RAID. I'm thinking the hardware on the Dell card will out-perform the SATA controller on the motherboard.
Am I right, or would I be better off to use the integrated controller from Intel?



One of the most beautiful aspects of PCIe is the automatic link width negotiation.

It is possible to insert a 1x width card, a 4x width card, and a 16x width card into a 16x slot wired in in 1x mode, 4x mode, 8x mode, or 16x mode and the protocol will automatically configure the connection to the highest commonly supported datarate and link width.

It is also possible to insert a 16x card into a 4x slot or even a 1x slot if the slot is open ended or the card is cut to the appropriate length (don't do this).

Pins should not be hanging in space if it's a 4x width card inserted into a 4x slot. Please post a picture so that we can take a look at it.
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July 6, 2014 9:10:40 AM

It has 76 pins on the larger "half" of the connector, so it appears to be an 8x device.
I don't have an 8x slot on this motherboard, but I do have 2 16x slots.
It beeps and shuts down the system when it is connected to either a 16x or an 4x slot.

The more I learn about this controller, the less I like it. Dell calls it an SAS-5/ir, but I guess it is really an LSI card. It is only capable of connecting 4 SATA drives, 3.0 Mbps, configured as RAID-0 or RAID-1. People have had trouble getting it to connect faster than 1.5Mbs and, unless you enable the cache, it suffers an 80% loss of write throughput. Then, it doesn't have a battery onboard so a loss of power can cause data loss or corruption. I suppose I could go to LSI and get the utility to update the firmware, but why? This card appears to be a piece of trash.

Wouldn't I be better off using the Intel on-board SATA RAID? That will be the topic of my next post.


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a c 169 V Motherboard
July 6, 2014 9:34:29 AM

thewiley1 said:
It has 76 pins on the larger "half" of the connector, so it appears to be an 8x device.
I don't have an 8x slot on this motherboard, but I do have 2 16x slots.
It beeps and shuts down the system when it is connected to either a 16x or an 4x slot.

The more I learn about this controller, the less I like it. Dell calls it an SAS-5/ir, but I guess it is really an LSI card. It is only capable of connecting 4 SATA drives, 3.0 Mbps, configured as RAID-0 or RAID-1. People have had trouble getting it to connect faster than 1.5Mbs and, unless you enable the cache, it suffers an 80% loss of write throughput. Then, it doesn't have a battery onboard so a loss of power can cause data loss or corruption. I suppose I could go to LSI and get the utility to update the firmware, but why? This card appears to be a piece of trash.

Wouldn't I be better off using the Intel on-board SATA RAID? That will be the topic of my next post.




The Intel PCH controller won't be any better than the LSI controller but if it provides enough ports for your use then it won't necessarily be any worse either
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July 7, 2014 6:12:02 AM

If you think performance will be comparable between the Intel on-board controller and the LSI expansion card, I will be much better off using Intel for the following reasons:

    6 drives instead of 4
    RAID-5 instead of RAID-1
    fewer points of potential failure
    lower power requirements
    the Intel hardware works and the LSI card doesn't.

Seems like a no-brainer. However, I have not been able to confirm that the Intel Rapid Storage Technology is a hardware-based controller. If it is actually software-based, wouldn't I be better off letting Server 2012 R2 handle the RAID-5 duties using "Storage Spaces"?
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a c 169 V Motherboard
July 7, 2014 1:20:39 PM

thewiley1 said:
If you think performance will be comparable between the Intel on-board controller and the LSI expansion card, I will be much better off using Intel for the following reasons:

    6 drives instead of 4
    RAID-5 instead of RAID-1
    fewer points of potential failure
    lower power requirements
    the Intel hardware works and the LSI card doesn't.

Seems like a no-brainer. However, I have not been able to confirm that the Intel Rapid Storage Technology is a hardware-based controller. If it is actually software-based, wouldn't I be better off letting Server 2012 R2 handle the RAID-5 duties using "Storage Spaces"?


The Intel PCH storage controller is considered to be a thin SATA/SAS port controller with a firmware-assisted software RAID. The PCH storage controller is accompanied by a BIOS/UEFI firmware driver which allows the storage volumes to be handled as a RAID volume. The only real difference between configuring a RAID at the BIOS/UEFI level and configuring a software RAID in Windows is that the firmware managed RAID can be booted from.
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July 7, 2014 2:14:51 PM

I'm a little disappointed to find out that the RAID controller on my motherboard is a "firmware-assisted" software RAID, whatever that is. It sounds like it will require a great deal of CPU attention. Even a quad-core (8 thread) i7 might be bogged down somewhat if it has to calculate parity on every byte written. I don't care about boot capability because I am using a dedicated boot drive. Maybe I'll try it both ways and run some benchmarks. Either way, though, I am going to need a good UPS so I can turn on the write caching. If the results are close, I'll go with the Microsoft solution because it is simpler and more flexible. The third option would be to go out and buy a real hardware-based RAID controller with onboard caching and a battery.
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a c 169 V Motherboard
July 7, 2014 2:28:15 PM

thewiley1 said:
I'm a little disappointed to find out that the RAID controller on my motherboard is a "firmware-assisted" software RAID, whatever that is. It sounds like it will require a great deal of CPU attention. Even a quad-core (8 thread) i7 might be bogged down somewhat if it has to calculate parity on every byte written. I don't care about boot capability because I am using a dedicated boot drive. Maybe I'll try it both ways and run some benchmarks. Either way, though, I am going to need a good UPS so I can turn on the write caching. If the results are close, I'll go with the Microsoft solution because it is simpler and more flexible. The third option would be to go out and buy a real hardware-based RAID controller with onboard caching and a battery.


RAID5 does perform quite poorly on the Intel PCH controller. If you wish to use RAID5 you should use a dedicated hardware RAID controller
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