2gb RAM OK but 4gb = BSOD

According to cpu-z, it's a Transcend DDR2 JM800QLU-2G PC2-6400 (400 MHz).

That's actually 800 mhz memory. PC2-6400 means that.

Here is the datasheet on your exact model. Do not change any voltages. The modules are intended to run at 1.7v to 1.9v. The standard 1.8v is perfect.

http://www.transcendusa.com/support/...-2G_2980-S.pdf

oh, i see. alright thanks for the information. :)

Thanks to torrentg for the information in this thread. I am using 4x1GB OCZ RAM at the moment and am waiting for my Windows 7 disk to arrive in the post. I shall keep this thread in mind when I install.

Unfortunately, it worked perfectly (after switching RAM Voltage to 2.1V) at first boot. Yey I thought, used the PC for a while and then shut it down. Let it be for a 24 hrs something and then rebooted - now I get a new type of bsod (this kind I have not recieved before, good or bad I do not know). Bsod is as follows:

c000021a { Fatal System Error }
The initial session process or system process terminated unexpectedly with a status of 0x00000000 (0xC0000221 0x001003a8)
The system has been shut down

Darn. I force power off, reboot, choose "Launch windows normally" instead of "Launch system repair" and everything works just fine. The previous bsod's also behaved in this way, after reboot all is ok. That's the most confusing part.

From what I read when I briefly checked on that error, it seems like it is possible it's due to an incorrect or faulty driver on the system.

I know this is for XP, but codes generally mean same thing or very similar in nature.

"This problem may occur if you install an inappropriate driver for your hardware"

"STOP: C0000221 unknown hard error" or "STOP: C0000221 STATUS_IMAGE_CHECKSUM_MISMATCH" error message occurs

Seems software related, not hardware.

Post a mindump so we can look at it. Upload to Rapidshare.

C:\Windows\Minidump

I will asap do the following:

1. Disconnect my DVD-drive to locate whether it is the cause of any of the problems. Also I will disconnect my card reader, which I reconnected after successful boot after ram voltage switch.
2. Post a minidump when I recieve next bsod (however the last bsod, saved no minidump file even though I have that option checked, so the only dumpfile I have is about a month old, and it is a different "kind" of bsod, prior to the voltage change.)
3. Check my windows files with sfc /scannow

I have already:

1. Updated BIOS to the latest version
2. Updated all drivers for all hardware including chipset and such, this was however pre the last install (since then I have formatted and some drivers might now be out of date), however that did not seem to solve the problem so I'm figuring there's no need for it now.

The sfc /scannow resulted in the following:
"Verification 100% complete.

Windows Resource Protection did not find any integrity violations."