I have a hp pavillion with 128mb ddr ram (pc2100), having checked with local shops and pc world i was told a 512mb ddr ram (pc3200) would work as long as i took the other out, i did this today and after installing got a bleeping noise every 2/3 seconds, the pc wouldnt boot up, i tryed it the other way round, no bleeping this time pc still woudnt boot up. i then thought ok best put the old 1 back in the same thing happened! it was fine b4 we took the old one out, please please help thanks

Go ahead and put the 512 stick back in, leaving the 128 out. Then pull the battery for about 30 seconds. Unplug the machine too. Then reinstall the battery and plug the machine back in and reboot it. It should work. YO

If you follow YO's suggestion, you will have to go into the BIOS & correct ALL the settings...hopefully you know how they were set. I'm not sure what "tryed it the other way round" means. Hopefully you reversed the stick in the slot? They're notched on the bottom & are only made to fit one way...if you forced it, you could have really messed things up ASUS A7N8X-X Athlon XP 1800+ 8.5 x 200MHz 1024MB PC3200 2.5-3-3-7 Asus A9550GE/TD 128MB WinME/WinXP Pro SP2

trouble is i dont no the settings and have never done it before, when i tried it the other way i meant just turned it around not upside down... The bizarre thing is i took the 128 out a few weeks ago to check it put it back in rebooted with no probs wotsoever!!

"when i tried it the other way i meant just turned it around not upside down..." I didn't mean upside down. RAM is meant to fit in the slot one way & one way ONLY! That's why there's a notch in it. If you reversed the stick, the notch would no longer correspond to the raised spot in the RAM slot. If you forced it into the slot anyway...you may have damaged the new RAM, and/or possibly the motherboard. ASUS A7N8X-X Athlon XP 1800+ 8.5 x 200MHz 1024MB PC3200 2.5-3-3-7 Asus A9550GE/TD 128MB WinME/WinXP Pro SP2

At reading the first answer I really hoped you meant just another slot but this last answer really sounds like you forced it inside in the wrong direction. This may fry board and ram and it looks like this happend because the old ram will not work anymore. Check the connectors on your ram to see if they are damaged. If they are damaged don't use the ram anymore. I guess you have at least 2 ram slots so if one of the two sticks looks okay (preferable the old one as it usually should run) put it in in the correct direction (check the fitting of the notch before pressing it in) and try to boot. I really hope you jast damaged the one slot but nothing else! BTW: !!!!!!!!!!!!!!!!! Always unplug the power supply if you work inside a computer because those those ATX psus still supply some amount of power even if the computer was switched out. That's necessary to be able to use the power switch or to start the computer via lan and so on!