Help.... AV8 issues with XMS3200C2PT - Bad memory?

[joelschlegel]

Ram Guy... I need your help! This is driving me crazy.....

 

System Specs:

Athlon 64 - 3500+

Abit AV8 (flashed to latest version... 19)

BFG 6800 Ultra OC

550W PS

2-200 Gig maxtor drives

 

I have recently added another gig of corsair XMS-3200-CP2 (Twinx) memory

(for a total of 2Gig) to my system and im now experiencing spontaneous reboots. So the system has 4 DIMMS XMS-3200C2PT. I purchased 2

Twinx paks of 1 Gig (4 512M dimms).

 

The problem seems to come into play when all 4 memory slots are populated and I try to set the DRAM up so that it runs at DDR400 (using either SPD or MANUAL settings for DRAM)

 

When setting the DRAM config to "auto" on the MB the system seems to run fine, however, it sets the memory bus speed to 170Mhz (DDR370) according to memtest86 (v1.5).

This seems strange to me since the memory is rated as DDR400

 

 

(following tests had the DRAM setting to SPD)

I tested each DIMM separate with memtest86 and all was fine

 

 

Then I tested 2 (new) DIMMS together... and that test was fine (in 1st 2 memory slots). Memtest reported memory bus @ 202Mhz / DDR 404

 

I boosted the DRAM voltage to 2.7 as you suggested to others on this forum

 

When all 4 slots are populated, and put the mb setting to anything other than AUTO, I get failures on test #5, 6 or 7. There were huge chunks of bad areas (330000 errors) on pass 1. the memory addresses were all over the place that were bad... seemed spread out over all modules.

 

Questions:

a) Is there any 'technical' reason why the memory bus speed would drop to 166Mhz (170 Mhz ) / DDR333 (DDR 370) when all 4 DIMMs are installed?

 

b) any recommendations to determine if it is a RAM issue or MB issue?

 

c) any recommendations on how to determine which module is bad

 

Other notes:

System has rebooted 2 x when all 2 gig is installed and the MB is set at

DRAM "Auto". If I put it at either SPD or MANUAL and set it to DDR 400

then the system isn't stable at all and reboots frequently. (when only 1 gig is installed, the system is stable).

 

If I left any pertinent information out... I can provide it..

 

Thanks in advance for your assistance!

[RAM GUY]

With AMD64 if you install more than 2 modules the CPU will try to set the memory frequency to DDR333. This is a limitation of the memor controller. But you can try and set the timings manually and please make sure that you set the command Rate to 2T or or AUTO.

Dim Voltage to +2.8 Volts:

CAS Latency CL=3.0

Row Cycle Time tRC Bios Default

Row Refresh Cyc Time tRFC Bios Default

Ras# to CAS# delay tRCD 3

Row to Row delay Bios Default

Min Ras# Active Time tRAS 8

Row Precharge Time tRP 3

Write Recovery Time Bios Default

Write to Read delay Bios Default

Read to Write Delay Bios Default

Refresh Period tREF Bios Default

Enable 2T Timing Enabled

Then test the system with http://www.memtest.org and make sure it's stable! In additon, what power supply are you using? I would suggest at least a 500 watt PSU with this config.

[joelschlegel]

Thanks for the quick response :-)

 

YES.. my Power supply is 550 watts (because of the piggish graphics card)

 

Followup question:

 

So if i had only 2 dimms of 1g each.. then I would get overall better performance (because the memory runs at DDR400 versus DDR333)

 

 

So there is a performance hit for having 4 dimms? I did not read this anywhere... can you enlighten me as to where you got this information?

 

Also... is this 'problem' still present if i used registered memory? I read that if you have large amounts of memory, you would be better off using registered memory...

 

Thanks in advance

[RAM GUY]

So if I had only 2 dims of 1g each.. Then I would get overall better performance (because the memory runs at DDR400 versus DDR333)

Yes, there is more loading on the memory controller when you add more memory and some chipsets/memory controllers will need the timings a bit more relaxed. It has always been this way with un-buffered memory.

 

So there is a performance hit for having 4 dims? I did not read this anywhere... can you enlighten me as to where you got this information?

Should be in the user manual; and the CPU white papers.

 

Also... is this 'problem' still present if i used registered memory? I read that if you have large amounts of memory, you would be better off using registered memory...

Yes, but there is only one load per module with buffered memory verses 20 loads with un-buffered memory. However, the MB you have will not support buffered AKA Registered memory. In addition, registered modules do not over clock as well because of the PLL Phase Lock Loop used with registered modules.

[joelschlegel]

Interesting.. thanks for your information. It cleared alot of things up

[RAM GUY]

No Problem, please let me know how you make out!