Buffalo PC3700 DDR (3)
Bluetooth 24th June 2003

Buffalo PC3700 DDR

 

Test Environment :

• ABIT IC7-G

• Intel P4 2.4C

• Tyan Radeon 9700Pro

• 2 x 256M Buffalo PC3700

• CPU Voltage : 1.75v

• AGP : 1.6v

• DIMM : 2.7v

We chose the P4 2.4C in this test because we know that the CPU FSB can easily reach 250MHz. To verify this, we ran the dual sticks at SPD with CPU running at 250MHz FSB and RAM at 200MHz. Ratio used = 5:4. It works perfectly. This verifies that the CPU can run 250MHz sync with RAM provided the ram sticks can take that speed running 1:1.

During the initial test, we noticed something, if you use SPD, the DIMMs are detected as DDR333 and will auto set the ratios in. In fact on the EPoX 8RDA3+, SPD also sets it to DDR333 running Async speeds. We are careful to note that we want to run sync bus in order to see how far we can push the DIMMs. All tests are done with performance mode set to disabled.

As this ram is rated PC3700 CAS3 , that means it should be able to run at max 233MHz memory FSB. That is to say if we run a ratio of 1:1, the CPU runs at 232Mhz, the RAM runs at 232Mhz too. We noticed that SPD reads CAS 2.5, 7-3-3. Performance mode set to Disabled. NO POST. We thought perhaps it should work at CAS 3, setting it to CAS 3, 8-4-4 doesn't help. It still won't POST.

At 228MHz, it POSTed but returns a BSOD. At CAS 3, 8-4-4, it can't even POST. At 225MHz, it went into Windows but it is not stable, the system rebooted. We settled for 223Mhz and turn on Performance mode to Fast at SPD (2.5-7-4-4).

Below are the scores :
 

Conclusion

In our test, we use two different platforms to test the least and most aggressive timings that works using a pair of DIMMs. Although the two DIMMs works in dual channel ddr system, I think it could perform better if it runs on a single stick.

We find that the CAS 3 rating is kind of weird. On both platforms we tested, it seems that whenever we set to CAS 3, the system won't boot. It happened on both boards. We thought it was the ram timings but it doesn't seem so. As we tune it to CAS 2.5, with the same low ram timings, it POSTs and works. It remains a mystery to us. Another thing that we noted is that if RAM is set to run in SPD mode, it will be recognised it as a DDR333 stick. This will lower the performance of the system if you are running a 400MHz Barton or a 800Mhz CPU.

Considering that it is a PC3700 CAS 3 module, we are not able to reach the DDR466 (233) levels using relaxed timings. The best effort was done on the IC7-G reaching 223MHz steadily using CPU:MEM at 1:1 and Ram timings at CAS 2.5-7-4-4.

Overall, the two modules works flawlessly at 200MHz~210MHz FSB at aggressive timings on AMD and works well under P4 at 223MHz. Although it is a 10MHz gap from the 233MHz (PC3700), it's stability rounds it all as a good choice for DDR400 systems if you were to run it at CAS 2.5 or even at CAS 2. Price at USD66 per piece, it is definitely worth considering.

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