DDR should not have anything like "2533". If it is DDR2-533, you can't put them together.
If both are DDR 400 (consider P4), you might be able to. I might still have some DDR 400 left and let me know if you need them.
I am a gadget sink and hate to see things go wasted. :)
DDR-400 is the highest it goes.
| Standard name | Memory clock (MHz) | Cycle time[4] (ns) | I/O bus clock (MHz) | Data rate (MT/s) | VDDQ (V) | Module name | Peak transfer rate (MB/s) | Timings (CL-tRCD-tRP) |
|---|---|---|---|---|---|---|---|---|
| DDR-200 | 100 | 10 | 100 | 200 | 2.5±0.2 | PC-1600 | 1600 | |
| DDR-266 | 133⅓ | 7.5 | 133⅓ | 266⅔ | PC-2100 | 2133⅓ | 2.5-3-3 |
|
| DDR-333 | 166⅔ | 6 | 166⅔ | 333⅓ | PC-2700 | 2666⅔ | ||
| DDR-400A DDR-400B DDR-400C |
200 | 5 | 200 | 400 | 2.6±0.1 | PC-3200 | 3200 | 2.5-3-3 3-3-3 3-4-4 |
