Look at the top right of the green circuit board where the red circle is on the photo. There may or may not be copper-colored lettering there. Look on the right side, but not as far over (where the blue circle is on the photo). There could also be lettering there.
If the code "IC1003" appears on the right (red circle on photo), your mother board is a TA-082. You WILL NOT be able to use the Undiluted Platinum modchip in your PSP.
If the code "IC6001" appears on the left (blue circle on photo), and there is NOTHING on the right, you have a TA-081 motherboard, and you WILL be able to use the modchip.
If there is some other code, you have another motherboard model, and you WILL be able to use the modchip.
The PSP in the photo is a TA-081 model, with the code "IC6001" on the left side, in the blue circle. It's difficult to see, with only the tops of the letters and numbers visible in the photo.