I have an ASROCK K7VT4A+ motherboard which was fitted with 2 sticks of 256mb PC2100 RAM.
The PC appeared to be slower and when I checked only 256mb of RAM was shown. Assuming that one stick was faukty I took the opportunity of replacing both sticks with a single stick of 512mb PC3200 RAM.
This is seen as 512mb in the BIOS but in Windows System Properties it is shown as 256mb - certainly the PC runs just as slowly.
I then replaced one of the 256mb sticks along with the 512mb and they are both shown in the BIOS but only 256mb is shown by Windows.
I have reset the BIOS in accordance with the makers instructions but with no effect
I am now completely lost!!!
Any help woud be more than welcome

Just done the Hardware Scan from this forum and iy reports that 768mb installed but only 256mb reported to operating system!!!!

I went looking for your mainbaord on the Asrock site and found this pop-up when I clicked on the link for your board (http://www.asrock.com/product/product_k7vt4a+.htm) -

Correction Notice K7VT4A+ FSB Jumper Setting Table on PCB R1.01 Silk Screen


Owing to PCB vender’s mistake in the production process, some of K7VT4A+ motherboards have incorrect FSB Jumper Setting Table on the PCB R1.01 silk screen. It will not cause any damage to your MB or CPU even if you follow this incorrect table to adjust the jumper setting. However, the system may not be able to boot properly if you use some of FSB 333 CPUs. If the PCB version of the MB you purchased is R1.01, please do not follow the FSB Jumper Setting Table on the PCB silk screen to adjust the FSB jumper setting. For correct information about the FSB jumper setting, please refer to the FSB Jumper Setting Table in the Quick Installation Guide bundled in the MB package. You can also find the correct FSB jumper setting table from below table or the user manual in ASRock Support CD.






The K7VT4A+
FSB Jumper position The Correct K7VT4A+ FSB Jumper setting Table



This could be your problem. Check the FSB speed of your CPU and set it according to the above table.



Regards
_____
Meck

Thanks for the reply.
However, the jumpers are at the correct setting and as I said originally 2X 256mb were recognized as 512mb until recently and now with either 1X 512mb OR 512mb+256mb installed all that is reported to the O/S is 256mb.
With 1X 256mb installed that's exactly what it sees/reports - 256mb.
It a m/board change the answer??
I have contacted Asrock and await a reply in the meantime any other ideas are more than welcome
Cheers