Dud DIMM, or just too slow?

[Lilt]

Hi There,

I recently assembled a system. I've built and upgraded a number of computers over the years, mostly for myself and family members/friends, probably about 10 machines in total. Pretty-much all of them have gone together without a hitch. This time, however, something isn't right.

I bought an 8GB DDR3 1333 dual channel ram kit to go with an M5A 78L-M LX and Phenom x4. However, the parcel went missing in the post over the holiday season. As the Phenom processor I bought also went out of stock, the company I bought it from were kind enough to replace the chip with a Bulldozer FX-4 at no extra charge.

The problem? I can only get one of the DIMMs to work. When both of them are installed, windows (Windows 7 Professional 64-Bit) reports that 8GB are installed but that only about 3.98GB is usable. I tested the two DIMMs individually, and found the system to boot when one is inserted but not when the other is. In addition, with the remaining DIMM that the system does boot with, I've had a couple of BSODs which is never really a good sign.

I was about to call the company to return the items, but when reading the motherboard memory guide I noticed a note about the bulldozer FX series processors supporting up to DDR3 1866 RAM... Significantly faster than my puny 1333 RAM. I have CPU-Z, but amn't 100% sure how to check exactly what speed the memory is running at. There is no clear "1333" or "1866" value in the system, nor do either of those values jump out at me on the BIOS screen. I had a look in the BIOS to see if I could downclock the system at all, but sadly couldn't see anything of the sort.

Also, I'm not overclocking this system... The Bulldozer FX is a welcome upgrade (larger cache) but I'm only using the stock cooler so don't plan to push the system at all.

Any ideas?

 

[jaquith]

Welcome to Tom's Forum!

Nobody's perfect... First, I would recommend BIOS version 0801 - http://www.asus.com/Motherboards/AMD_AM3Plus/M5A78LM_LX/#download Correct the FX CPU's support DDR3-1866 but they also support DDR3-1333; faster depends on both CAS Latency + Frequency. It seems obvious that the BIOS is shutting-down one of the sticks. More often with (2) sticks on a (2) DIMM MOBO it's a bad stick -- bad together. Sometimes slightly increasing the DRAM Voltage can overcome the problems, but in your case IMO RMA the RAM.

I assume FX-4100

Q - What exact RAM do you have?
Q - What ASUS Utilities did you install? *

* If you installed AMD OverDrive Utility, ASUS Ai_Suite or even ASUS EPU-4 ; uninstall them. The interfere with the BIOS and can cause problems.

 

[Lilt]

Hi jaquith,

Thanks! I've read toms hardware off and on for years, probably ever since I built my first computer (AMD K6-2 350 with CreativeLabs Riva TNT) but not joined the forums until now.

I've downloaded the 0801 BIOS, I'll give it a shot when I have some time. You are correct that it's an FX-4100.

A1: The RAM was 2x4GB DDR3 1333 DIMM CL9, they have a EUDAR logo on them.
A2: I did install most of the utilities that came under the drivers heading on the disk... Mildly annoying that they try to get Norton past you as a driver, but whatever. I'll try removing them, but think the problem may have first appeared before I installed them (IIRC the first POST I peeked at saw only showed 4GB ram).

Cheers!

 

[jaquith]

Use CPU-z to identify either the CAS timings in the 'SPD' tab; it'll either be listed as 'XMP' or the right-most JEDEC; CPU-z -> http://www.cpuid.com/softwares/cpu-z.html My general experience is DDR3-1333 should always work properly with defaults, but it's worth a shot to manually set the RAM. I never heard of 'EUDAR' RAM - might ne cheap RAM.

Unfortunately, those Utilities are always running in the background and interfere with the BIOS.

When updating the BIOS use ASUS EZ Flash 2; see How to -> http://www.tomshardware.com/forum/289507-30-what-flash

I have some errands and I'll be back in a couple of hours.