It's generally false to say that FAT PS2s perform worse than slimlines... because they have a similar hardware configuration (Although the chips and PCB layout used varied from model to model).
Originally Posted by resincake
If you want a FAT PS2... I'll recommend that you avoid the SCPH-5x0xx series if you want to play backups.
Beware that older FAT PS2s (SCPH-3x00x) have picky lasers (They can't read low-quality discs and DVD+R discs without wearing themselves out)...... (Use only high-quality DVD-R discs like Verbatim DVD-R!!)
If you want a slimline... just avoid the SCPH-70xx and SCPH-90xx series if you want to have the least problems.
The SCPH-700xx series has a lot of problems with it's laser unit... and the SCPH-900xx series (With BIOS v2.30) won't boot FMCB.
My advice to you if you want to get a new PS2:
If you don't need the internal HDD and just want to play games off discs... just get a SCPH-750xx/SCPH-770xx/SCPH-790xx PS2. Otherwise, get a SCPH-3x00x series FAT PS2.
BTW about your new laser: Did you "activate" it (Something about melting something called the "Anti-static point" ) and adjust it's pots?
Can you determine whether the PS2 even attempts to read the disc (The laser lights up... even if it doesn't move about)?
I think that you should have already got the right laser for your model (Different slimline models used different lasers)... since you seem to know what you're doing (Purchasing/replacing the laser).
The EE clock speed was was increased starting from 1 PS2 revision... but I think that it was before the SCPH-3x00x series. The increase was very marginal: From 294MHz to 299MHz.
i think some ps2's have a tiny bit faster EE clock. but the difference is marginal and doesn't really impact anything.
it is possible though that some performance improvements could be observed, because most slim ps2's have EE and GS in one chip. but i am no expert in ps2 internals.
Sony replaced the EE and GS chips with a single chip in slimlines to save space and to reduce manufacturing costs.
SCPH-10000 S. MINOKAMO v1.01 (Defunct)
SCPH-10000 S. KISARAZU v1.00 (faulty)
SCPH-15000 S. KOHDA (With warranty seal!) :D
DESR-5100 S. EMCS