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Yet another problem where only half the memory is available

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  • Memory
Last response: in Memory
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September 5, 2014 5:55:55 AM

I've seen many posts on this and they all seem to have different answers. I've tried everything I can think of so I decided it's time to put my specific case out there to see if any of you can help. Build details are below.

First off, I've already ensured the "max memory" box in msconfig is not checked.

Initially, I tried 2x2GB Patriot Sector 5 DDR3 1333MHz 9-9-9-24. Using either slots 1 & 3 or 2 & 4, Windows showed 4GB Installed and 1.98GB usable.

Then I switched to Patriot Viper 2x4GB DDR3 1600MHz. Again I made sure to use the correct slots as indicated by the motherboard manual and now Windows shows 8GB installed and 3.98 usable. This motherboard has no on-board graphics card, so I know that's not eating up the RAM.

I've also tried dropping the speed on the 1600MHz RAM to 1333MHz, but that didn't change anything. I ran memory test on the 2x2GB RAM and it was fine. The 2x4GB is brand new, so I a haven't run the memory test on it yet, but based on the behavior when I switch RAM, I don't think it's a bad RAM problem.

Finally, CPU-z is showing that I'm running Single Channel instead of Dual. I think this is the key point since I keep showing about half the RAM usable.

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I've replaced the CPU-z output with more info on my build here:

Motherboard: GA-990FXA-UD3 rev4.0
CPU: AMD Phenom II X4 955 Black
CPU: Cooler: CoolerMaster Hyper 212 Plus
RAM: Patriot Viper 2x4GB DDR3 1600MHz PV38G160C9K
Graphics: Dual EVGA GTS 450 1024MB in SLI mode
Power Supply: CoolerMaster GX 650W

More about : problem half memory

a b } Memory
September 5, 2014 6:06:50 AM

From Task Manager, Performance, what does it show for -

Total, Cached, Available and Free

Then From Resource Monitor, what does it show for -

Hardware Reserve, In Use, Modified, Standby and Free
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September 5, 2014 6:43:47 AM

Total: 4076
Cached: 1738
Available: 2453
Free: 795

Hardware Reserve: 4116
In Use: 1602
Modified: 68
Standby: ~1741
Free: ~676

When I had the 4GB memory in, about half was Hardware Reserved as well.
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September 5, 2014 9:52:53 AM

I forgot to mention I have also removed the CPU and checked that there are no bent pins. Then I re-installed and made sure I didn't tighten the heat sink down too much.
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September 5, 2014 3:24:32 PM

Adding more pieces to the puzzle: I am unable to boot with a single DIMM in any of the slots. I get no POST at all when there is only one DIMM installed. Should the GA-990FXA-UD3 rev4.0 be able to boot with a single DIMM? The motherboard manual is a bit vague in that it only describes Dual Channel operations for RAM and says nothing about single channel.

Thanks again...
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a b } Memory
September 5, 2014 3:45:56 PM

Hello,

Please try another CPU with your motherboard or test your CPU/memory with another motherboard; the culprit could be the CPU, as it has built-in memory controller... You cannot also rule out the motherboard, despite good reviews and reliability for this particular model.
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September 5, 2014 4:54:04 PM

Yup, I know it uses Dual channel RAM. Does that automatically mean it won't operate single channel?

Any particular reason you recommended that specific RAM? I don't think it's even on the motherboard supported RAM list and it's 1866MHz which the mobo manual says requires an AM3+ CPU which I don't have. (Of course the RAM I've tried so far isn't on the support list either.)
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September 7, 2014 3:32:29 PM

New Update: I replaced the CPU with an FX-8320 and I'm still having the same problem. Additionally if I put memory in all 4 slots, ensuring I am matching up the channels properly I still have about ~half the RAM showing usable.

Slot 1: 4GB Patriot Viper3
Slot 3: 2GB Patriot Sector 5
Slot 2: 4GB Patriot Viper3 (matched with slot 1)
Slot 4: 2GB Patriot Sector 5 (matched with slot 3)
Usable: 5.96GB

Whether I put in 4GB, 8GB, or 12GB I end up with half (minus about 0.04 GB) usable in Windows 7.

It seems the only thing that is common is the motherboard at this point. Ideas?
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a b } Memory
September 7, 2014 5:15:15 PM

CosmoSparks said:


It seems the only thing that is common is the motherboard at this point. Ideas?


It appears the motherboard is faulty. Before RMA it though, put all BIOS settings to "default" or do a CMOS reset (follow exactly the instructions from your motherboard's manual), maybe some setting is messing with the memory (it was something like "memory hole remapping" if I remember correctly, but since the 64-bit era I don't think it is used anymore).
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September 15, 2014 6:08:46 PM

CMOS clearing didn't solve the problem either. I'm working with Gigabyte now to see what the issue is and possibly RMA. I'll let folks know what the resolution is.
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