Memory not fully recognised on X58

[sniper_sung]

I installed i7 960 and 3 x 2GB Kingston 1333 C7 on Gigabyte UD7 and everything worked fine. 6GB memory passed 24 hours of memtest.

Then I replaced UD7 with ASUS P6TD Deluxe and everything worked fine.

Then someday I noticed that only 4GB is recognised by BIOS and Windows. Only CPU-Z and Everest can recognise 6GB. I tried to change the order of memory modules and different slots and found that Slots A1 and A2 were not working. Any memory modules installed in A1 or A2 were just missing from BIOS. Machine didn't post if only one memory module was installed in A1.

Then I removed the CPU and checked for bent pins but didn't find any. After re-seating the CPU, Slots A1 and A2 were working again, but C1 and C2 stopped working. Thus I decided to RMA P6TD.

Later the shop notified me that during their tests all 6 slots on P6TD were working and they refused to issue a replacement. They're shipping back the P6TD on Monday. Then I suspected there might be something wrong with the i7 960 CPU.

I installed the 960 onto UD7 again, first time boot, Slots A1 and A2 were not working. After re-seating 960, Slots B1 and B2 were not working. Then I tried several times re-seating the 960 but it was always Slots B1 and B2 not working. I made a conclusion that the memory controller of this 960 is broken. Perhaps P6TD is more picky with CPUs.

Then I got an i7 980X and installed it onto the UD7. All slots were working. Then I removed 980X and re-installed the 960 back onto the UD7. Strange enough, all slots were working again.

Then I got 3 x 2GB Corsair XMS3 1600 C9, and installed all 6 modules into all 6 slots. All 12GB are now recognised by both 960 and 980X.

I'm still waiting for the P6TD to be sent back and test both CPUs on it.

So what the hell is the problem here? How do I determine which part is faulty?

[mpilchfamily]

Key bit of information is missing. What OS are you using?

If its a 32 bit OS then that would be your problem. You'll need a 64 bit OS in order to take full advantage of all 6GB of RAM.

[sniper_sung]

Key bit of information is missing. What OS are you using?

If its a 32 bit OS then that would be your problem. You'll need a 64 bit OS in order to take full advantage of all 6GB of RAM.

Sorry it's Windows 7 x64. If I were running x86 Windows I wouldn't be able to see 6GB at all unless I hack PAE.

[[XC] Oj101]

And the BIOS would see 6GB. Did the shop test more than one slot at a time or just put a 1GB stick in each slot sequencially? Get them to retest with three or six slots at a time.

[Sam_oslo]

Probably you are using too tight timings, UD7 doesn't like it.
Loosen up timings, and you will see all RAM.

[eva2000]

I installed i7 960 and 3 x 2GB Kingston 1333 C7 on Gigabyte UD7 and everything worked fine. 6GB memory passed 24 hours of memtest.

Then I replaced UD7 with ASUS P6TD Deluxe and everything worked fine.

Then someday I noticed that only 4GB is recognised by BIOS and Windows. Only CPU-Z and Everest can recognise 6GB. I tried to change the order of memory modules and different slots and found that Slots A1 and A2 were not working. Any memory modules installed in A1 or A2 were just missing from BIOS. Machine didn't post if only one memory module was installed in A1.

Then I removed the CPU and checked for bent pins but didn't find any. After re-seating the CPU, Slots A1 and A2 were working again, but C1 and C2 stopped working. Thus I decided to RMA P6TD.

Later the shop notified me that during their tests all 6 slots on P6TD were working and they refused to issue a replacement. They're shipping back the P6TD on Monday. Then I suspected there might be something wrong with the i7 960 CPU.

I installed the 960 onto UD7 again, first time boot, Slots A1 and A2 were not working. After re-seating 960, Slots B1 and B2 were not working. Then I tried several times re-seating the 960 but it was always Slots B1 and B2 not working. I made a conclusion that the memory controller of this 960 is broken. Perhaps P6TD is more picky with CPUs.

Then I got an i7 980X and installed it onto the UD7. All slots were working. Then I removed 980X and re-installed the 960 back onto the UD7. Strange enough, all slots were working again.

Then I got 3 x 2GB Corsair XMS3 1600 C9, and installed all 6 modules into all 6 slots. All 12GB are now recognised by both 960 and 980X.

I'm still waiting for the P6TD to be sent back and test both CPUs on it.

So what the hell is the problem here? How do I determine which part is faulty?

reasons and solutions all listed at http://i4memory.com/ramdetect/ - enjoy

[sniper_sung]

And the BIOS would see 6GB. Did the shop test more than one slot at a time or just put a 1GB stick in each slot sequencially? Get them to retest with three or six slots at a time.

I'm not sure how they tested it but I suppose a ?2 slot wouldn't work unless the corresponding ?1 slot is installed with a memory module (e.g. B2 wouldn't work unless B1 is loaded). So to verify each slot works they had to use at least 2 modules at a time.

[sniper_sung]

Probably you are using too tight timings, UD7 doesn't like it.
Loosen up timings, and you will see all RAM.

But it was P6TD which started to dislike tight timings first...

reasons and solutions all listed at http://i4memory.com/ramdetect/ - enjoy

Thanks! Just scanned through it and I think I've basically tried everything except manually configuring everything without using XMP. I'll test it when the P6TD is back.

[Johnny87au]

Either your timings are way to tight, try setting them manually, or you have faulty ram, try memtest..see how you go..