This is a complication of two posts that I have made on my blog available here:
Accessing the Recovery Menu on PSP | Karol Krizka Useful Settings in the PSP Recovery Menu | Karol Krizka
I recommend visiting the above links to see the latest updates to this tutorial. I basically cover how to access the Recovery Menu on the M33 firmware, and I talk about several useful settings that I found there. I hope I have not made any factual errors in documenting them, but if you see any, point them out!
Accessing the Recovery Menu
Start by fully turn off your PSP by holding the power button for a couple of seconds. After the screen goes dark, you know it’s off, and you can let go. Then press the big R button on top, and hold it. Next turn on the PSP (still holding the R button!), and you will see the recovery menu. Simple, eh?
The following settings are available on the 3.52 M33-4 custom firmware. I have no idea if they are available for older versions, but if you want to upgrade, then you can check out my
earlier tutorial for instructions.
Configuration -> Skip Sony logo
This setting can will skip the Sony logo that you see when you start your PSP from a shutdown, which should speed up the boot time of the PSP a bit. However I think that the setting is useless in most cases, because I usually put my PSP into Sleep mode that does not display the Sony logo. But I have enabled this option anyways, because from time to time I do need to shut off the PSP completely.
Configuration -> Hide corrupt icons
To install a homebrew game that has been compiled for FW1.5, you have to copy two directories to your PSP memory stick. One is the actual application, and the other (the one that ends with a %) is used to help to launch it. However the second folder will be counted as another game by Sony’s XMB menu, and will be displayed as “Corrupted Data”, because it is not an actual PSP application. If you install a lot of homebrews, your XMB might become very cluttered. But this can be fixed with the Hide corrupt icons setting option on the M33 firmwares. Just enable it, and all the garbage entries in your XMB Application section will be gone. This is the most useful setting in the custom firmwares, and I suggest everyone enables it.
CPU Speed -> Speed in XMB
The processor in your PSP can run at several speeds, with the default being 222Hz. There is no way to change that in the official firmwares, but in the custom ones it is a piece of cake. I suggest that you set the speed to 75Hz, because that is the slowest possible speed. Your XMB does not need much processing power to run comfortably, so running it at 222Hz is a waste. Running at a lower clock speed does not require as much energy, and will increase the battery life of your PSP. Just press the X button after you have selected this option until you see it currently set to 75.
I run my PSP at this speed without any problems while I use it as an MP3 player. However I have not tried to watch a video, so you might experience some problems there because decoding of video
requires much more power. I will cover how to change the clock speed of your PSP from the XMB in a later post.
CPU Speed -> Speed in UMD/ISO
This setting sets the speed of your CPU while you play a game from an UMD or from a dumped ISO. I set mine to 333Hz, which is the fastest possible speed, to reduce the load times in many games. This is not overclocking your PSP, so it is completely safe. It has been designed to run at 333Hz, Sony just decided to underclock it to 222Hz in order to increase the battery life. If you run your games from an ISO, the 333Hz setting is recommended because you are already saving energy by loading from your memory stick, therefore your battery life will not be affected as much.
Finding the tutorial and sharing it took a bit of work, but there are
several free ways you can thank the people that make them. Just visit
this post for more info 
Accessing the M33 Recovery Menu and Some Useful Settings
QUESTION ABOUT BOTH PSP PHAT OR SLIM PM ME.
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