- PC Memory: Just the Facts
- The New Arms Race: DDR3-1800 RAM
- Hardcore DDR2 RAM by Corsair, G.Skill, OCZ and Patriot
- Overclocking 9 Value-Priced DDR2-800 Kits
- Corsair's PC10000 Super-Ober-Uber-RAM Sets Sails
- Corsair's XMS2 Dominator: The World's Fastest DDR2?
- Live Memory Test: Overclock 'Em Till They Crash
- Tight Timings vs High Clock Frequencies
- Navigating the Memory Upgrade Jungle
- In Search of True DDR2 Bleeding Edge Memory
Source: Tom's Hardware US – Keywords: ddr3, 1333, speed, latency, shootout
Topics: Buyer's Guides
Syndication:
Test Settings: Lowest Stable Latencies
Because of the previously mentioned "Boot Strap" limitations, we had to select different FSB speeds to test DDR3-1333 and DDR3-1600 data rates. But how could we do that without throwing the rest of our speeds off?
Lacking any 5:3 DRAM to FSB clock ratio required to test DDR3-1333 with an FSB-1600 processor, we instead must compare DDR3-1333 to DDR3-1066 using FSB-1333, and also compare DDR3-1600 to DDR3-1066 using FSB-1600.
Only two CPU speeds correspond to both FSB-1333 and FSB-1600: These are 2.00 GHz CPU clock and 4.00 GHz CPU clock. Since this started out as an overclocking article, the 4.00 GHz speed was selected. The CPU multipliers needed to reach 4.00 GHz at FSB-1333 and FSB-1600 is 12 x 333 MHz and 10 x 400 MHz, respectively.
| Latency Test System Hardware | |
|---|---|
| Motherboard | Asus Maximus Extreme Rev. 2.01G
Intel X38, BIOS 0501 (10/30/2007) |
| Socket 775 Processor | Intel Core 2 Extreme QX9770 "Yorkfield"
(FSB-1600, 45 nm, 3.20 GHz, 12 MB L2 Cache) |
| Hard Drive | Western Digital WD1500ADFD-00NLR1, Firmware: 20.07P20
150 GB, 10,000 RPM, 16 MB cache, SATA/150 |
| Graphics Card | Foxconn GeForce 8800GTX, P/N: FV-N88XMAD2-OD
NVIDIA GeForce 8800GTX - 768 MB |
| Power Supply | OCZ GameXStream OCZ700GXSSLI - 700W |
| System Software & Drivers | |
| OS | Windows XP Professional 5.10.2600, Service Pack 2 |
| DirectX Version | 9.0c (4.09.0000.0904) |
| Platform Drivers | Intel INF 8.3.1.1009 |
| Graphics Driver | NVIDIA Forceware 163.75 |
Since the Asus Maximus Extreme proved instrumental in diagnosing the boot strap issue, it was retained for memory latency testing.

Four-core processors use memory a little more effectively than dual cores and our highest latency test speed of DDR3-1600 matches the highest memory ratio afforded FSB-1600 processors. We used the only FSB-1600 processor available, which was Intel's Yorkfield-based Core 2 Extreme QX9770.

Game benchmarks are significantly limited by graphics performance, so we included a powerful GeForce 8800GTX from Foxconn.

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"Because cycle time is the inverse of clock speed (1/2 of DDR data rates), the DDR-333 reference clock cycled every six nanoseconds, DDR2-667 every three nanoseconds and DDR3-1333 every 1.5 nanoseconds. Latency is measured in clock cycles, and two 6ns cycles occur in the same time as four 3ns cycles or eight 1.5ns cycles. If you still have your doubts, do the math!"
Based off of the cycle-based latencies of the DDR-333 (CAS 2), DDR2-667 (CAS 4), and DDR3-1333 (CAS8), and their frequences, you come to the conclusion that each of the memory types will retrieve memory in the same amount of time. The higher CAS's are offset by the frequences of the higher technologies so that even though the DDR2 and DDR3 take more cycles, they also go through more cycles per unit time than DDR. How is it then, that DDR2 and DDR3 technologies are "better" and provide more bandwidth if they provide data in the same amount of time? I do not know much about the technical details of how RAM works, and I have always had this question in mind.
Thanks
Bandwidth = Rate at which you can get the "goodies"
7-7-6-24-2t at 1333Mhz or
9-9-9-24-2t at 1600Mhz
This is FSB at 1600Mhz unlinked. Is there a method to calculate the best setting without running hours of benchmarks?