Performance regressions with C'n'Q, C1E, SB750
after running a few tests I have come along some major performance regressions when using AMD's power saving options.
- MB: ASUS M4A79T Deluxe
- CPU: Phenom II X4 810
- Memory: 8GB DDR3
- SSD: Intel X25-E
- HD 4850
- Ubuntu 9.04, Kernel 2.6.30
Test tools were hdparm -t and ET:Quake Wares at max setting 1920*1200.
C'n'Q on, C1E on
System Idle: SSD 135 MB/s, ETQW 24 fps
System Full Load with prime: SSD 185 MB/s, ETQW 30 fps
C'n'Q on, C1E off
System Idle: SSD 150 - 170 MB/s, ETQW 26 fps
System Full Load with prime: 180 - 190 MB/s, ETQW 30 fps
C'n'Q off, C1E off
System Idle: SSD 200 - 210 MB/s, ETQW 36 fps
System Full Load with prime: 180 - 190 MB/s, ETQW 31 fps
System SSD performance drastically depends on power saving options and from the results it also looked like it depends on CPU load, so I have done a few other tests.
C'n'Q off, C1E off, 1000 Mhz fixed
System Idle: SSD 170 - 180 MB/s
C'n'Q off, C1E off, 1600 Mhz fixed
System Idle: SSD 200 - 210 MB/s
As the results show, the SSD maxed out at a CPU Clock of 1600 Mhz. It looks like the SB750 doesn't support SATA natively and offloads alot to the CPU.
What is wrong with AMD? It can't be that you have to turn off all the power saving options and keep the CPU under low load just to get normal performance for one SSD!