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Specs beforehand (Upgraded HP m8530f): AMD Phenom X4 9550 @ 2.20 GHz / HIS 256MB Radeon HD4350 GDDR2 PCI-E / 6.0 GB PC2-6400 DDR2 RAM / 750GB SATA Seagate Barracuda HDD / ASUS M2N78-LA / CoolerMaster 500W PSU

So, this computer comes stock with 5.0 GB of RAM. So in the four slots, there is a 1 GB - 1 GB - 2 GB - 1 GB configuration. Today, though, I got another 2GB stick, so now I have a configuration of 1 GB - 1 GB - 2 GB - 2 GB. However, after I booted up... I went to Computer Properties and it says that I only have 5.0 GB Usable memory. However, I checked online and for Windows 7 Pro 64-bit, the max supported memory should be much much more.

Any ideas? Are there questions like this already? (oops)

EDIT1: for Sim...

enter image description here

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Have you upgraded the BIOS? There is a BIOS update for your model (HP m8530f) on the HP website that might do the trick M2N78-LA Motherboard BIOS update improves security support, and fixes incorrect memory size being reported in Vista when 4GB or more is installed.

There is a good page on the HP Site that walks you through upgrading to Windows 7 and covers know issues and solutions etc.

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I flashed the BIOS when it had Vista 64-bit... would I still need to do it now? – Wesley Jan 29 '10 at 3:20
Well I guess that depends on which BIOS version you used. The one in the link is from July last year and is version 5.29. Which one did you install? – Sim Jan 29 '10 at 3:30
I'm not exactly sure if I installed that one then... but the only one available on the site is for Vista 64-bit, and it won't install on my 7 64-bit... – Wesley Jan 29 '10 at 3:53
If you run "System Information" then the system summary will tell you which BIOS version you are using. Try installing it with the "Run as Administrator" option and set compatibility to be Vista. – Sim Jan 29 '10 at 22:44
Wesley, Did you work out which BIOS version you had installed? – Sim Feb 2 '10 at 19:53

What does your BIOS says? That's what I would look first. If BIOS says 6 you know the problem is with windows and vice-versa.

Another very useful thing to do is run CPU-Z. Cpu-z will not merely tell you how much RAM you have, it's gonna tell you how much ram is installed per slot. Chances are the slot order will match your motherboard order, you just have to figure which one is first. If one of the slot shows empty, try to remove that RAM and go back in cpu-z to confirm you removed the right one. Mark it.

Then try to remove all RAM except the 'faulty' one and try it alone - can you boot? If no, try a different slot, but it may be bad ram. If you can boot, it means your motherboard is just having a hard time with dealing with the 4 at once (different models, etc.). You can help it by reordering the slots, slacking the timings, reduce memory speed a little, etc from your BIOS.

I am running 8gb here and windows 7 sure detects them all.

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I'm using Speccy and it recognizes them all. – Wesley Jan 29 '10 at 2:43
CPU-Z also recognizes them all – Wesley Jan 29 '10 at 2:49

Assuming the memory is correctly detected in the BIOS, run MSCONFIG, open the Boot tab, click Advanced Options, make sure that Maximum Memory is not capped.

enter image description here

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There is no cap on the max memory. Any other ideas? – Wesley Jan 29 '10 at 1:54
@Wesley - check the box and use 6144 as max – Molly7244 Jan 29 '10 at 1:55
Setting the cap doesn't change anything... it still says 5.0 GB usable. – Wesley Jan 29 '10 at 2:44
@Wesley - memory modules are identical in terms of specifications? tested with memtest86+? – Molly7244 Jan 29 '10 at 3:16
One of them is slightly different from the rest, but they are all PC2-6400 DDR2 RAM... would that be a problem? – Wesley Jan 29 '10 at 3:21

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