Memory doesnt run well at PC2-8500

I've just built a PC with the following specs:

- Gigabyte GA-MA790GP motherboard AMD 790GX chipset AM2+ socket
- AMD Phenom X4 9850 Black Edition
- Memory is 4GB (2 x 2GB) G.Skill DDR2 PC2-8500
- Video is onboard ATI Radeon HD 3300 (has sideport memory 128MB)
- Win XP Pro

Now I checked the motherboard and CPU to make sure they supported PC2-8500 memory, which is supposed to run at 1066 MHz, but for some reason my system runs it at PC2-6400 (800 MHz). This is confirmed from the BIOS settings and CPU-Z info.

I have been able to change the BIOS settings and manually set the memory at PC2-8500 and boot to windows, but with that setting I tend to get spontaneous reboots! System is unstable.

The only thing I could think of is the fact that the onboard video memory has a dedicated sideport memory of 128 MB + it uses some of my system memory. Actually BIOS has the setting for video memory as "Sideport + UMA". Could this all be solved by purchasing a dedicated video card?

The system is running fine at PC2-6400, but I would like to be able to run the memory at PC2-8500.

I appreciate your input.
5 answers Last reply
More about memory doesnt 8500
  1. JEDEC memory standards do not rank memory at a PC28500 1066MHz. level. There is no 8500 standard. All PC28500 is considered higher clockable PC26400. PC28500 will always default to PC26400 800MHz. 1066MHz transfer rate must be set manually. PC28500 will many times require more voltage than PC26400 to run at faster transfer rates. In BIOS besides the speed, adjust the voltage to Mfg. specifications. Timings also. Your system crashes should cease.
  2. Yep, badge has pretty much covered it. You just need to check your RAM's voltage and timings. More than likely, if i were a guessing man, your RAM probably needs 2.1v and timings of 5-5-5-15. Some G.Skill RAM needs 2.0v, some need 2.1v. The usual timings at 1066Mhz are 5-5-5-15. HOWEVER, your RAM could be different. It should be listed on the RAM's packaging, G.Skills' website, or the merchant's website from which you bought the RAM.
  3. Sigh. Another one who believed the advertising.
    badge said:
    JEDEC memory standards do not rank memory at a PC28500 1066MHz. level. There is no 8500 standard. All PC28500 is considered higher clockable PC26400.
  4. pretty sure the timings were right at least. not sure about the voltage. will double check. i'll give it a try when i get a chance. will get back to u.
  5. - sometimes support is added in the BIOS. Check for a BIOS update.

    FYI, in real world usage you would see no real difference between 800MHz and 1066MHz. There's even an article about that at TomsHardware with benchmarks of various games showing no difference in frame rates.

    Yes, there are times it can make a difference but they are rare, and probably would only occur in specific encoding tasks that are trying to max out your CPU thus finding a possible memory limitation.

    So if you don't get 1066MHz don't worry about it (and your RAM will be far less prone to failure).
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