iMac 5k 27" (late 2015) - brand new SSD has very slow write speed. Please help.
Hi everyone.
I have scoured this forum for days and still not found the solution for my problems so now it's time to lay it all out there and hopefully somebody can help. I am growing desperate.
Here is the spec of my iMac
and the highlights:
Model Name: iMac
Model Identifier: iMac17,1
Processor Name: Quad-Core Intel Core i5
Processor Speed: 3.2 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB
System Firmware Version: 499.40.2.0.0
OS Loader Version: 540.120.3~22
SMC Version (system): 2.33f12
Serial Number (system): C0******G7L
Hardware UUID: 156E8C2F-8667-5CC8-A253-C04AB5CDBC88
Provisioning UDID: 156E8C2F-8667-5CC8-A253-C04AB5CDBC88
The Mac is 6+ years old and until this year worked brilliantly. I started having some issues with storage and thought that the hybrid drive was failing. Given their reputation and age, this seemed probable and so I replaced it with an SSD.
Crucial BX500 1TB 3D NAND SATA 2.5 Inch Internal SSD - Up to 540MB/s - CT1000BX500SSD1
and here is the system report:
Intel 10 Series Chipset:
Vendor: Intel
Product: 10 Series Chipset
Link Speed: 6 Gigabit
Negotiated Link Speed: 6 Gigabit
Physical Interconnect: SATA
Description: AHCI Version 1.31 Supported
CT1000BX500SSD1:
Capacity: 1 TB (1,000,204,886,016 bytes)
Model: CT1000BX500SSD1
Revision: M6CR061
Serial Number: 22*******E55
Native Command Queuing: Yes
Queue Depth: 32
Removable Media: No
Detachable Drive: No
BSD Name: disk0
Medium Type: Solid State
TRIM Support: Yes
Partition Map Type: GPT (GUID Partition Table)
SMART status: Verified
Volumes:
EFI:
Capacity: 209.7 MB (209,715,200 bytes)
File System: MS-DOS FAT32
BSD Name: disk0s1
Content: EFI
Volume UUID: 0E239BC6-F960-3107-89CF-1C97F78BB46B
disk0s2:
Capacity: 1 TB (999,995,129,856 bytes)
BSD Name: disk0s2
Content: Apple_APFS
Since this replacement I have struggled to get the Mac to work well.
After much searching it seems that the issue is the disk write speed. Using Blackmagic speed test I am clocking write speeds of less than 10 MBS. This is obviously way lower than satisfactory.
I initially did a migration of all my info via time machine. Have reinstalled OSX more than once. Today I wiped the SSD and reinstalled OSX and even before transferring files and reinstalling software, the problem persists. Very occasionally I run the speed check and get results up in the 400s MBS, but within seconds this drops of drastically back into at most 20MBS.
I am desperate now. For anyone who takes the time to help, I thank you in advance.
I'll do my best to answer any questions you might have.
thanks
Justin
[Edited by Moderator]
iMac 27″, macOS 12.6
