9550 - hynix 2.5ns problems

[V0rt3x]

hi guys..
i'm new on the forum.. i knopw u r the best, so i was wondering if you could help me..
i just bought a gecube radeon 9550GU..
i was happy at the beginning because i've seen the 2.5 ns hynix memory chips.. they should be able to run at 800Mhz.
the strange thing is that the card wasn't clocked as usual...it runs at 400gpu / 500 mem (instead of 430 / 550 as a normal 9550 does).

i've tryed overclocking it and the best i got was 650MHz memory clock.. i'm far away from 800.. and it doesn't want to go higher...

the strangest thing is that i see no artifacts... the image is clear, but 3dmark2k1 simply crashes at higher memory clocks.
with ati tool i get artifacts at aropund 750MHz.. of course, 3dmark is impossible to run at such clock rates.

i thought that the memory chips could be undervolted, but they get quite hot...
i've placed some heatsinks on them.. but no improvement...

please tell me what could be wrong with this card...
thank yuo in advance

PS:
fast writes oon/off makes no difference

PPS:
please tell me if it's safe to change the cas latency in atitool from 3 to 2...
can you give me some safe but agressive timings? (timings 1/2/3 from atitool)

[JasonDTM]

Look for 9600XT voltmods, thats basically what the card is, Its most likely running out of voltage, and 75% of the cards, volts dont help the situation as I've read they've added 15mhz at the most (Most I've seen)