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Question SSD choice - SATA port on motherboard versus AMD chipset m.2 slot

PingSpike

Lifer
Feb 25, 2004
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I'm using the primary CPU driven m.2 slot on my x470 motherboard for something else, so it is not available.

I have a m.2 drive and I'm thinking of putting it in the secondary slot (which is only pcie 2.0 4x and comes off the chipset) to replace a SATA drive as my primary OS drive.

Any reason this is a bad idea or a performance regression? I know the chipset slots share bandwidth so that's a disadvantage, and sometimes they have a latency penalty (?) but I would still think it would win out against a decent SATA SSD. I'm mostly concerned about loading games, not really benchmarks.
 

Insert_Nickname

Diamond Member
May 6, 2012
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Even PCIe 2.0 x4 is still a massive improvement on SATA. You don't have to worry about bandwidth, since X470 has a PCIe 3.0 x4 connection to the chipset. PCIe 2.0 x4 is roughly equivalent to PCIe 3.0 x2. So there is plenty of bandwidth for other devices. There is a very small latency penalty using chipset provided lanes, but I doubt you'll ever notice it.
 

solidsnake1298

Senior member
Aug 7, 2009
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Check your motherboard's manual. On some boards it may force the GPU slot down to x8 PCIE lanes when both M.2 slots are occupied. Before you commit try inserting the 2nd SSD and run GPU-Z to see how many lanes your GPU is using.
 
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PingSpike

Lifer
Feb 25, 2004
21,588
445
126
Check your motherboard's manual. On some boards it may force the GPU slot down to x8 PCIE lanes when both M.2 slots are occupied. Before you commit try inserting the 2nd SSD and run GPU-Z to see how many lanes your GPU is using.
I'll lose the third 4x wired slot on this board when that m.2 slot is populated but that is OK with me. There are already 2 GPUs in the other slots running 8x.
 

PingSpike

Lifer
Feb 25, 2004
21,588
445
126
Even PCIe 2.0 x4 is still a massive improvement on SATA. You don't have to worry about bandwidth, since X470 has a PCIe 3.0 x4 connection to the chipset. PCIe 2.0 x4 is roughly equivalent to PCIe 3.0 x2. So there is plenty of bandwidth for other devices. There is a very small latency penalty using chipset provided lanes, but I doubt you'll ever notice it.
Good point on the bandwidth, I'd forgotten that it already had basicaally double on that end of things.

Does SATA usually have a bit of a latency penalty anyway versus m.2? In my case its either SATA or chipset. Its funny because now that I think about it on Intel platforms most people were always running m.2 off the chipset so I'm probably just being nitpicky to begin with.
 

Insert_Nickname

Diamond Member
May 6, 2012
4,185
756
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Does SATA usually have a bit of a latency penalty anyway versus m.2? In my case its either SATA or chipset. Its funny because now that I think about it on Intel platforms most people were always running m.2 off the chipset so I'm probably just being nitpicky to begin with.
Compared to "native" ports from the CPU on AM4, yes, there is a small difference. Again, not really even worth mentioning.

That's really the beauty of the AM4/FP5-6 platform. It's more of a breakout I/O chip, then a traditional chipset. Ryzen is a full SoC in itself.
 

aigomorla

Cases and Cooling Mod PC Gaming Mod Elite Member
Super Moderator
Sep 28, 2005
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I'm mostly concerned about loading games, not really benchmarks.
is that 1 extra second really that important then losing 3-4 fps from going down from 16x to 8x on the pci-e on what could happen if you do use a pci-e nvme. (would need to see the rest of your config).

But its been hashed and tested.
NVME for gaming is not much of an improvement over SSD.
And in competitive FPS, there is absolutely no advantage, because they make you wait in a loadup zone while everyone is map loading anyhow.
So it only helps in games with long map zone transitions, which many don't have lately, as people hate loading screens, and loads on on the fly dynamically after the first initial reload.

I have a 4TB nVME, and a 4x4TB SSD R0 array.

I notice almost 0 different between the two.
I would probably not even notice a different outside a couple of seconds, if it was even a single SSD vs a nVME.
 

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