Two memory chips: good on single but not work with both on

[4thpc]

7 year old HP PC with two memory slots with max memory 512 MB (2x256).

I had two 128 MB RAM and it's too slow so I bought identical Patriat PC100 256 MB chip.

With all posisble combinations I had tried all work fine but the one I wanted most does not work.

Case 1 does NOT work and the PC always loop on starting and won't get into windows (XP Pro)
Case 1: slot1 256 MB, slot2 256 MB

the following cases all work fine
case 2: slot1 128 MB, slot2, 256 MB (tried with both chips)
case 3: slot1 256 MB, slot2, 128 MB (tried with both chips)
case 4: slot1 only with any single 256 MB or 128 MB,
case 5: slot2 only with any single 256 MB or 128 MB,
case 6: slot1 128 MB, slot2, 128 MB

Tried to unplug power cord and waited more than a few minutes and this trick wouldn't solve the issue. So what's going on on those two identical chips? They should be compatible with eath other. If either one can work independently and is compatible with other chips why they can't work with both on?

thanks.

[jlreich]

I would try resetting the CMOS by pulling the CMOS battery out for at least ten minutes. Install the new sticks and power up. You will need to reset system time/date.

If that doesn't work then the system isn't going to take both of them. It isn't the ram that is at fault. PC100/133 systems are picky about ram density. Likely the ram is higher density and the system can only handle one stick without problems.

[saphalline]

SDRAM's SPD implementation was far from perfect. If it doesn't "just work" and there are no BIOS updates that fix it, you'll have to try different RAM. Not much else you can do with an OEM system.

[4thpc]

Thank you guys. I tried to remove the CMOS battery and reset the time and it did not work. It's indeed low density RAM.

http://cgi.ebay.com/NEW-256MB-PC100-SDRAM-168pin-Low-Density-Best-Price_W0QQitemZ180292424940QQcmdZViewItemQQptZLH_D efaultDomain_0?hash=item180292424940&_trksid=p3286.c0.m14&_trkparms=72%3A1234%7C66%3A2%7C65%3A12%7C39%3A1%7C 240%3A1308%7C301%3A1%7C293%3A1%7C294%3A50

I also tried to update the BIOS from HP website and both the new BIOS HP provided won't go through. Great job by HP.

I guess I will either use just 384 MB or look for new RAM.

[jlreich]

It's always been hit and miss with SDRAM. Your best bet for compatible ram is to go to Crucial (http://www.crucial.com/) and use their lookup tool. You are going to pay more for it, but if you buy it through their tool it is guaranteed to work or your money back.

[4thpc]

The BIOS could find the two 256 MB, showing Bank 0 with 256 MB and Bank 1 with 256 MB. It also read it from 1 to 512 MB (not exactly 512 but 510, the last number I saw, because the increment can be 2, 4, or a bigger number). So the BIOS seems to know the max ram is 512MB and somehow it could not communicate this with windows XP, and this cause the problem. Correct me if my guess is wrong. The funny thing is HP's BIOS to the machine could not be installed. No wonder people rate their PC low.

Yes, I either pick new RAM or use the 384 MB I have.

[jlreich]

Yes, I either pick new RAM or use the 384 MB I have.
That's pretty much your choices.

The funny thing is HP's BIOS to the machine could not be installed. No wonder people rate their PC low.
To be fair to HP we are talking a rather old machine. Seven years is jurassic in computers terms, and it is more generations behind current systems than I can count on both my hands. HP probably officially stopped supporting that system over five years ago.

Actually, if you think about it, the fact that a seven year old system is still up and running is a testament to HP. ;) Actually, now that I think about it, I have an HP that is a little newer than yours I use as a dedicated firewall machine still chugging away 24/7. :cool:

[mjc]

My biggest complaint about HPs...inadequate power supplies. The PSUs that HP stuffs into those things have barely enough power to handle the stock setup. The other thing and this is mostly due to the poor PSU...lack of upgrade capability.

[jlreich]

inadequate power supplies
They are. As are most OEM's. The original one in my firewall machine went out a long time ago.

[4thpc]

My biggest complaint about HPs...inadequate power supplies.

I agree. My power supply died about 3 years ago and I replaced with one that has more power.

My sarcastic appraise to HP's great job is that the two BIOS updates they put on their website were made specifically to the model I have. However, none of them could be succesfully installed. I guess mine must be a little different than others.

It's good to see a 7 year old still run. I keep it mainly for backup in case my other machines can't be used or for older people visiting my home who needs to check email or browse web.

[mjc]

What is the error you are getting when you try to run the update?

[4thpc]

"File does not contain the same BIOS part number. Press any key to reboot"

This error shows at the very end of the updating of BIOS and I saw the progress went to up to 98 or 99%. I tried to keep only the original hardware as much as I could and reset original BIOS to its default. I still got this error.

Another BIOS update has to be done at MS DOS. As I chose to update as the instruction says, it gave me a line that it's not the time to go to the menu. It asked me to press 1 or 2. I got this line no matter chich choice I took.

[larrymoencurly]

eBay memory isn't famous for having good quality. Download MemTest86 ver. 3.5a (http://www.memtest86.com/download.html) and test the memory with it, both one module at a time and both modules together. There's a good chance that each 256MB module has bad bits. It's possible that going into the computer's BIOS setup and changing the memory timing parameters will help, especially slowing the memory bus speed from 133 MHz to 100 MHz. However any memory that doesn't work reliably at all its default settings should be replaced.

Crucial.com (http://www.crucial.com) has an online utility that can scan your computer and tell you what types of memory are compatible with it. It's possible that 512MB modules (modules, not chips -- chips are those black rectangular plastic things soldered to the modules) are supported by your computer, and XP Pro runs a lot better with 1GB.

[minus-sign]

Your BIOS situation is apparently, not an all-too-uncommon problem. Checking the Hp support forum can give you a few ideas for how to get your BIOS upgraded.

My guess is that you have not upgraded this BIOS in the 7 years the PC has been in use (many people don't). You may need to "step-up" your BIOS gradually. Instead of trying to jump from the OEM to the latest version, look for earlier releases and try installing them. Then, if one works, gradually step up in release dates until you reach the latest BIOS.

[mjc]

Yep, minus-sign, that's about the size of it...HP does something, at least in that era, that almost nobody else did...the latest version of the BIOS did not always incorporate all the changes made in the previous updates. They used to have sort of 'milestone' updates...you had to have at least that update for any future ones to work. And they never labeled them as anything special...but if you could find the release notes for the updates, it might say in there that this particular release is dependent upon a previous one.

[4thpc]

OK, I finally solved this mystery. One stone on two birds, both BIOS update and booting of XP with full memory (2 x 256MB).

I rarely used this old machine. The other day I thought I could bring this up to catering the curiosity about PC and abuse on the keyboard and mouse of a 2 year old.

The reason that I did not solve the issue was the lack of clarity of HP BIOS update. When I found the PC could not boot to XP with full memory I tried to update the BIOS. The BIOS from HP (2.11 and 3.07) failed to flash successfully.

The old BIOS on my PC is version 2.09. HP later released 4 BIOS updates for this machine: 2.10, 2.11, 3.04 and 3.07. On the readme file they all listed that the Pavilion 7855 is on the target list. However, 2.11 and 3.07 could never be applied to this machine because the BIOS part number does not match. And that's the two BIOS I found and used last time. From the board there is no way to see the board manufacturer and model. Only this time I found the 2.10 and 3.04. I flashed them on the PC and it went through.

BIOS 2.09 --> 2.10 --> 3.04 --> XP booting successfully with full memory. After 3.04 was applied the BIOS showed PnP(OS) Yes. Before the 3.04 BIOS it would let you choose Windows98/2000 or Others.

Any other path or path involving 2.11 or 3.07 would fail.

During the process I had tried many things, such as replacing 40 connector hard drive cable with 80 connectors to accomodate the Ultra DMA drive, using much powerfull power supply, removing any parts not involving booting the windows, etc. It turned out they were not at issue at all. All it needs is the BIOS 3.04 update. I did find that with the better power supply the machine work faster. I also want to give a tip to people who have the same or similar problems. If the window could not boot and loop in BIOS, try to boot with floppy disk and then see if you can access your hrad drive with OS. The 3.04 BIOS instruction is to update BIOS with hard drive. The BIOS could see the hard drive but when I tried to access it from A:> to C: drive, it informed me Invalid drive. So at booting stage the OS hard drive is simply not accessible. How could windows boot in this case? So I copied the BIOS update files to a floppy, used Windows Me Startup disk to boot to A:>. Then I take the floppy out and inserted the floppy with 3.04 BIOS update. After I flashed 3.04 BIOS issue was solved. Another thing worth mention is that after I updated the BIOS and window XP booted, Microsolft need to reactivate the windows because hardware changed dramatically. In fact only memory chips changed from 256MB + 128MB to 256MB + 256MB.

The machine is not worth much value. But it's a little fun to solve the problem.

Hope this may help some people.