iMac M3 and SSD

Hi,

This is a MacBook Pro case, though the 512 in the MacBook Pro with M3 is twice as fast. The 256 models are slower because they only put one NAND stack in the computer instead of two which double the bandwidth.

I think iMac is also 256GB model slower than 512GB one.

I remember seeing on other Web sites that 256 GB SSDs in the M2 notebooks were slower than 256 GB SSDs in their M1 counterparts. The reason being that M1 machines with 256 GB SSDs were using two 128 GB flash chips, while M2 machines with 256 GB SSDs were using higher-density 256 GB flash chips. This derived the M2 Macs with the 256 GB SSDs of the ability to perform two flash operations in parallel.

The "slow" 256 GB SSDs still turned in speeds higher than any USB 3.0 / SATA SSD could. Just not the speeds we've come to expect from internal NVMe SSDs (or from Thunderbolt 3 / NVMe SSDs).

I have the m2 air 15 inch 512, and the m3 iMac 256 . My m2 air is two times faster in ssd speed; I am very disappointed I didn't go with the m3 512 iMac because I had no idea it was slower, do not buy a 256 iMac if you want 3000 plus ssd speeds.

Per Youtube test the 256GB is much slower than the 512. the 1TB has the fastest read/write speeds.

There's no indication they are different speeds. Unless cost is an issue, I would always choose the largest available. It can't be expanded if needed.

kaz-k's reply reminded me there have been reports that the 256GB SSDs are slower in the laptops. It may also be true for the iMac.