B
Barry Watzman
SIS R659 RDRAM launched: 9.6 GB/s for the Pentium 4 (HARDWARE)
By Johan
Wednesday, November 5, 2003 5:20 PM EST
RDRAM could make a surprising comeback, thanks to SIS. SIS and Rambus
launched today the SISR659, a chipset that is capable of using 4 (16
bit) 1200 MHz RDRAM channels. When you do the math you'll see that those
four RDRAM channels can deliver no less than 9.6 GB/s (4 x 2 bytes x
1200) to the chipset. Of course, this awesome amount of bandwidth is
going to be bottlenecked by the 800 MHz FSB of the Pentium 4.
To get better performance out of the otherwise wasted bandwidth, a
Dynamic Look-ahead Cache and Adaptive Page Management can be found
within the R659 chipset. The Dynamic Look-ahead Cache Intelligently
prefetches data into an on-chip chipset cache, and lowers the latency of
the memory subsystem. Normally, a pagehit on a well-designed DDR 400
controller like the i875p results in a 5 cycle latency: 2 cycles through
the controller, 2 cycles for the CAS latency (assuming CAS = 2) and 1
cycle back through the controller. The look ahead cache reduces this to
two cycles. If a page hit does not occur, PC1200 RDRAM should have a
latency that is very similar to DDR400. Rambus and SIS claim that the
latency of the RDRAM channels vary between 10 (cache) and 35 ns, while
DDR400 memory latency should vary between 25 and 35 ns.
A few benchmarks (source: Rambus), R659 versus i875P (Dual DDR400, 2-3-3-6)
Quake 3 fastest: 7% faster
Return to Castle Wolfenstein: 7% faster
Content Creation 2003: 3% faster
SpecViewperf PRoe: 12% faster
SpecViewperf DRV-09: 9.5% faster
SpecViewperf UGS-03: 3% faster
Seems pretty good, but I think the real power of the ASUS board can only
be unleached by the overclockers community. The ASUS P4S13G board has
two 32 bit RIMM sockets which have to be populated by two 1200 MHz dual
channel (2x16 bit) RDRAM RIMMS. The board is also equipped with 3 SATA
and 3 PATA IDE connectors.
The ASUS board that will be coming out in the next weeks, has the option
to use a 800 MHz FSB/PC800 setting. Simply overclock the FSB and keeping
the mem in sync should give some pretty good results. I am betting it
will come close to 1200 MHz FSB given the right CPU, based on my
previous experiences with ASUS RDRAM boards. Samsung seems very
enthusiastic and claims that by Q1 of 2004, 75% of their RDRAM chips
will capable of 600 MHz DDR or 1200 MHz, with another 10% hitting 800
MHz DDR or 1600 MHz.
By Johan
Wednesday, November 5, 2003 5:20 PM EST
RDRAM could make a surprising comeback, thanks to SIS. SIS and Rambus
launched today the SISR659, a chipset that is capable of using 4 (16
bit) 1200 MHz RDRAM channels. When you do the math you'll see that those
four RDRAM channels can deliver no less than 9.6 GB/s (4 x 2 bytes x
1200) to the chipset. Of course, this awesome amount of bandwidth is
going to be bottlenecked by the 800 MHz FSB of the Pentium 4.
To get better performance out of the otherwise wasted bandwidth, a
Dynamic Look-ahead Cache and Adaptive Page Management can be found
within the R659 chipset. The Dynamic Look-ahead Cache Intelligently
prefetches data into an on-chip chipset cache, and lowers the latency of
the memory subsystem. Normally, a pagehit on a well-designed DDR 400
controller like the i875p results in a 5 cycle latency: 2 cycles through
the controller, 2 cycles for the CAS latency (assuming CAS = 2) and 1
cycle back through the controller. The look ahead cache reduces this to
two cycles. If a page hit does not occur, PC1200 RDRAM should have a
latency that is very similar to DDR400. Rambus and SIS claim that the
latency of the RDRAM channels vary between 10 (cache) and 35 ns, while
DDR400 memory latency should vary between 25 and 35 ns.
A few benchmarks (source: Rambus), R659 versus i875P (Dual DDR400, 2-3-3-6)
Quake 3 fastest: 7% faster
Return to Castle Wolfenstein: 7% faster
Content Creation 2003: 3% faster
SpecViewperf PRoe: 12% faster
SpecViewperf DRV-09: 9.5% faster
SpecViewperf UGS-03: 3% faster
Seems pretty good, but I think the real power of the ASUS board can only
be unleached by the overclockers community. The ASUS P4S13G board has
two 32 bit RIMM sockets which have to be populated by two 1200 MHz dual
channel (2x16 bit) RDRAM RIMMS. The board is also equipped with 3 SATA
and 3 PATA IDE connectors.
The ASUS board that will be coming out in the next weeks, has the option
to use a 800 MHz FSB/PC800 setting. Simply overclock the FSB and keeping
the mem in sync should give some pretty good results. I am betting it
will come close to 1200 MHz FSB given the right CPU, based on my
previous experiences with ASUS RDRAM boards. Samsung seems very
enthusiastic and claims that by Q1 of 2004, 75% of their RDRAM chips
will capable of 600 MHz DDR or 1200 MHz, with another 10% hitting 800
MHz DDR or 1600 MHz.