PC-133 CAS2 RAM nor running at 133MHz ?

[Majesty]

Hello,

I have bought 256MB of Crucial PC-133 CAS2 RAM(Part No.: CT32M64S4D7E), and I just can't make it run at 133MHz. I have a Pentium III 550E running at 733 (5.5x133) and when I set the SDRAM/FSB Frequency at 1/1, it freezes in Quake3 (I don't even reach the Main Menu) and it must freeze in other games too. The only working configuration is 4/3. Someone might be able to explain this to me?

Thank you!
--------------
P3 550E@733
Asus P3V4X (BIOS 1006.2)
256MB of Crucial Cas2 RAM(Part No.: CT32M64S4D7E)
Pioneer DVD-Rom 303S SCSI
Yamaha CRW8424S SCSI
Quantum FireBall KX 13.6G
Quantum FireBall LM 20G
Quantum FireBall KA 13.6G
Quantum FireBall TM 3.2G
SB Live! Value
Adaptec SCSI 2940U/UW Card
ATi TV-Tuner
Aopen 10/100Mbits NIC
Asus V7700 GeForce2 GTS32 (Detonator 6.50)
Windows Me
--------------

 

[thermite88]

CL or CAS Latency is the amount of time in nanoseconds or clock cycles between a request to read the memory, and when it is actually output. SDRAMs are typically referred to as CL2 or CL3, with CL2 parts being faster.

The user, i.e. you, selects the CL in the motherboard BIOS. If the SDRAM is fast enough, it will run stable in CL2. Most of today's SDRAM comes with a EEPROM call SDP (Serial Presence Detect). The SDRAM module manufacturer load the timing information into this SPD ROM. The user can allow the motherboard to read the SPD and set the timing or CL accordingly. The user override the SPD settings when he wants to overclock.

Therefore, the user can find out what the SPD timing recommendation is by allowing the SPD to set the CAS Latency. Some manufacturer, such as KingMax, publishes the SPD content in their specification sheet. There are also utility program that dump the SPD contect. SANDRA's commercial version comes with a SPD read module, SPDINFO.EXE.

<< However, the manufacturer's SPD timing does not necessarily represent the SDRAM's true speed. For example, Crucial rates their SDRAM using 7.5 ns chips as PC-133/CL2. The Crucial has no overclock margin and most user cannot run much above 140 FSB. On the other hand, the Infineon PC-133/CL3 SDRAM also uses 7.5 ns chips and many users have reported running stable at 150 FSB @ CL2 and faster. >>