Memory not detected. Installed 16gb, BIOS only reads 4gb.

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derpaderp

derpaderp

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Dec 9, 2014
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First time poster. So I have two identical machines with the following specs:


  • Tyan i5400xt S5396 motherboard
    700w power supply
    2x quad core Xeon cpus
    4x Kingston 667 DD2 ECC 2gb sticks, (8gb)
,

Retiring 1 system to use for spare parts, and so have installed the spare and identical 8gb RAM into the active system to give 16gb (all DDR2 667 ECC 2gb modules). Thinking about loading up the 2 GPUs (SLI able) into the 1 active system but haven't touched that yet)

Mobo allows up to 64gb but after installed additional ram BIOS and Windows (7 ultimate 64bit) now only reads 4gb, despite 16gb installed. Removing spare memory to return to original 8gb also only detects 4gb...
Have successfully updated BIOS as a recent version mentioned memory reading issue. No change, still only 4gb usable ram.
Any suggestions?
 
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pecul1ar

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Dec 20, 2011
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...and double post. Alright lets use this to add this tidbit, which I found on this site:
http://www.tyan.com/manuals/m_s5396_120.pdf

Channel Single Dual Four Four
DIMM SLOT
DDR2 FBDIMM1 x x x x
DDR2 FBDIMM2 x
DDR2 FBDIMM3 x x x
DDR2 FBDIMM4 x
DDR2 FBDIMM5 x x
DDR2 FBDIMM6 x
DDR2 FBDIMM7 x x
DDR2 FBDIMM8 x

..darn, nevermind. Basically you have to insert the dimms into slots 1, 3, 5, 7. Slot 8 is the nearest to the mobo power slot, slot 1 is the furthest.
 
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derpaderp

derpaderp

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Dec 9, 2014
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Thanks for the response Pecul1ar. Mobo only has 8 DIMM slots, and Tyan manual does say for 4 sticks use slots 1, 3, 5 and 7. (this was the original config). By installed the spare ram I'm now using all 8 DIMM slots.
I have reseated the ram, vacuumed out carefully for dust and tried sticks in different orders....
 
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derpaderp

derpaderp

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Dec 9, 2014
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Oh Derp me. Well when i say vacuum, I mean nothing was touched, nozzle held above at a distance whilst blowing out dust (vacuum there to suck up the dislodged dust)
Nevertheless, the spare machine hasn't been vacuumed and is having the exact same issue. (16gb installed, only detects 4gb). Both systems used to work with 8gb (4x2gb sticks in slots 1,3,5,7).

Would this have anything to do with power supply? voltage to DIMMs? i.e I've had to swap out the power supply previously and may have not connected something? I've followed the Tyan manual on power cable connection, etc.
 
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pecul1ar

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Dec 20, 2011
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If you've seen the amount of memory detected then you've POST'ed and had connected all power cables properly.

One other trick i've learnt is to add the sticks incrementally, eg. 2gb, 4gb 6gb 8gb~ etc. Some sticks can be universally inserted to any slot, while other sticks only work in specific slots. Clean out the DIMM contacts with a pencil eraser then populate 1,3,5,7 then 2,6 then 4,8. Or maybe 2,4 then 6,8.
 
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derpaderp

derpaderp

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Dec 9, 2014
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Thanks - have previously added in just 1 stick in DIMM slot1 to give 2gb. Then slot3 to give 4gb. Then slot 5 to give... 4gb. Then slot 7 to give... 4gb. Haven't tried even number slots on their own yet, will do next.
....How do you mean 'clean with pencil eraser' ??? Do you mean the contacts on the actual memory modules?

Will tackle this and report back in about 20 hours.
 
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derpaderp

derpaderp

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Dec 9, 2014
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Ok, through trial and error have discovered 2 sticks don't respond, and a 3rd stick has a missing gold contact strip near one end of the module.
This means I've at least got my active system detecting 8gb ram again with 4 sticks installed.

Adding in the 5th working stick doesn't give me 10gb though. (i'm assuming they need to be installed in pairs? However having only 1x2gb stick in DIMM slot 1 works fine and gives me 2gb detected...

About to clean the 2 sticks that don't respond with an eraser. Can't see any visible damage on these.
 
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derpaderp

derpaderp

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Dec 9, 2014
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Ok so no way around it, it appears I have 3 dud sticks, 5 good ones. Can't see any documentation to specifically state memory NEEDS to be installed in even pairs for this mobo but i'm going on general knowledge to assume that there is no way to get my 5th good stick to be detected (which would give me 10gb ram) unless I look to acquiring new sticks. ...DIMM slot1 seems to be the exception so that the system can run on just 1 memory stick... no?

So next question - if i'm to get new ram, can i mix say, 4gb or 8gb modules with my existing 2gb modules? Is that a done thing?
 
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