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November 27th, 2018 09:00
Optiplex 740-can only boot with one DIMM
Trying to fix an Optiplex 740 with AMD Athlon 64 X2 3800+ cpu and running Windows 7 Ultimate 64 bit for a friend. It came with 1GB DDR2 DRAM sticks installed in DIMM 1 and DIMM 2. It stopped booting with both DIMMs installed, no errors it just turns on and promptly shuts off. It boots fine with either DIMM installed in DIMM 1 but is very slow. For a few months it had worked fine with the ram installed in DIMM 1 and DIMM 3. Now though it only boots with either one of the ram sticks installed in DIMM 1. Both sticks, individually, passed a run through Memtest 86. I'm wondering if a replacement CPU might resolve the problems?
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fireberd
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November 27th, 2018 11:00
Have you tried DIMM 2 and 4, that is the second set for dual channel operation?
I would rather suspect the motherboard (or memory if its not the original) rather than the CPU.
Considering the age of this machine (the manual has a 2008 publish date) carefully examine the capacitors on the motherboard. Older motherboards in this era had some problem with bad capacitors (puffed up top).
imaddicted2u
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November 29th, 2018 09:00
Thank you for the reply. Either of the 2 matched pair of ram sticks will boot in any slot. But won't boot as a pair.
Tried:
Dimm1+Dimm2 (original)
Dimm3_Dimm4
Dimm1+Dimm3
Dimm2+Dimm3
Dimm2+Dimm4
Manual say populate Dimm1 or Matched pair in Dimm1+Dimm2 then Dimm3+Dimm4
I do see 2 bulged 1800μF 6.3v capacitors near the DIMM sockets, the rest look ok. I'll try replacing those and see what happens.