I'm trying to add RAM to HP Pavillion 8776C - going from 256mb (two 128mb sticks) to 512mb (two 256mb). System is running WinXP.

Bought 256mb 168-pin dimm 32mx64 sdram unbuff pc133 cl2 low profile.

I pulled out 128mb and put in a 256mb to give PC 384mb. System runs like a champ!!!

I pulled out the second 128mb and put in second 256mb to give PC 512mb. Problems galore. Range from reboot right away (can't even get to WinXP logo), to reboot at WinXP logo (once). Tried Safe Mode, etc - basically can't get past the Safe Mode option screen.

I thought RAM was bad, so got company to send new one. Try that, same result, only maybe got farther. Problems range from reboot right away (can't even get to WinXP logo), to reboot at WinXP logo (several times got this far), to reboot when desktop/wallpaper appear (several times), to reboot when bring up first application (Outlook), to reboot when bring up multiple applications (Outlook, EXCEL, IE). Tried various combinations of the three 256mb and no combination is stable.

Used MemTEst utility, ran tests of 384mb config - no errors.

Ran tests of 512mb config - thousands of errors on Test 7 (random number or something like that).

Ok - so is there simple answer here? wrong memory ordered - then why does 384mb work? is there jumper/switch/thingamabob to click, pull, push, change? if so, anylinks to instrux? I looked for my system info and on HP site - can't find any info.

Any ideas/suggestions greatly appreciated.

Maybe that memory chip you installed last is not compatible with your motherboard.

Your system amy be limited to 384MB of system ram.

You dont mention if you are using dual sided or single sided chips.

If your machine only has two slots for chips it may not be able to handle two double sided chips. It may do fine with one single sided and one dual sided but give you the problems that you describe with two dual sided chips.

Memory for HP Pavilion 8776c

Standard Memory : 128MB
Maximum Memory : 512MB Memory Banks : 2
Available Memory Sockets : 2

HPPC000064MP1536A 64M PC-133 module for HP No. P1536A memory
$ 27

HPPC000128MP1537A 128M PC-133 DIMM for HP No. P1537A memory
$ 31

HPPC000256MP1538A 256M PC-133 DIMM for HP No. P1538A memory
$ 56

Sorry, I DO NOT mean to imply I am selling anything. I just did a cut and paste from a site to show your system should be able to go to 512 meg...

Even though some people use the word DIMM they dont always mean to say Dual Inline Memory Module... Sometimes they really mean Single...

I've got single sided (if that means the black rectangles are only on one side). Same as the 128mb sticks.

I got the dimm 133 etc, etc confirmed and double checked this many times on website, sales sheet, chip label - tho not HP brand - got Crucial instead - does Crucial have "good" stuff?

And double triple checked this HP is supposed to handle 512mb and the answer is yes every time.

Note -when I go into the BIOS, it shows 512mb when both 256mb sticks are in, and similarly, shows 384mb when one 256mb and one 128mb are in.

I'm not getting much help on HP Forum as of yet.

somebody at work suggested IRQ problems - i don't know anything about that, but would that explain why 384mb works, and 512mb doesn't?

any and all ideas welcome - there's gotta be something here.

At this point I would suggest you try HP Ram modules...
Did your supplier guarantee compatibility...
Everything says the box will handle 512meg... That is a non-issue...

hi,
I finally got to talk to a tech support rep who knew his stuff. The skinny: this machine and WindowsXP have these kinds of problems with 512mb.....even tho supposed to handle, it doesn't.

he wondered if BIOS upgrade might work, but I've been all over forums/support boards, and for this motherboard (Asus AV7-VM) - I'm SOL. HP is only source without risking blowing the board, and HP doesn't have upgrade.

So, I accept 384mb as max. If and when I decide I need more, it's new board, or new machine.

c'est la vie

I had the same problem with my HP only i got it up to 384mb ram. 32x64 might be too high of a density for it, as was the case with my computer. Did you try looking at pc100 ram? here is a site that will scan your comp and recommend what ram you might need www.4allmemory.com sorry dont mean to dig up old thread, but if he does check this again, it might be helpful.

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