FIRST LOOK: SiS 755FX for Socket 939 Athlon 64
by Wesley Fink on December 16, 2004 12:05 AM EST- Posted in
- Motherboards
Memory Stress Testing
Our memory stress test measures the ability of the Winfast to operate at its officially supported memory frequency (400MHz DDR), at the lowest memory timings that OCZ PC3200 Platinum Rev. 2 modules will support. All DIMMs used for stress testing were 512MB double-sided (or double-bank) memory. To make sure memory performed properly in Dual-Channel mode, memory was only tested using either one dual-channel (2 DIMMs) or 2 dual-channels (4 DIMMs).| Stable DDR400 Timings - One Dual-Channel (2/4 DIMMs populated) |
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| Clock Speed: | 200MHz |
| CAS Latency: | 2 |
| RAS to CAS Delay: | 2T |
| RAS Precharge: | 10* |
| Precharge Delay: | 2T |
| Command Rate: | 1T |
Using two DIMMs in Dual-Channel 128-bit mode, the memory performed in all benchmarks at the fastest 2-2-2-10 timings at default voltage, which was the only memory voltage available.
| Stable DDR400 Timings - 4 DIMMs (4/4 DIMMs populated) |
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| Clock Speed: | 166MHz |
| CAS Latency: | 2.0 |
| RAS to CAS Delay: | 2T |
| RAS Precharge: | 10* |
| Precharge Delay: | 2T |
| Command Rate: | 2T |
Tests with all four DIMM slots populated on the 755FX required a 2T Command Rate with 4 DIMMs in two dual channels. This is the pattern seen on other top-performing Socket 939 boards. However, without a 200 (DDR400) setting in BIOS, 4 DS DIMMs booted at DDR333. This is a common occurrence on other Athlon 64 motherboards, but most other boards allow a selection of DDR400 in BIOS to force DDR400 with 4 DS DIMMs. Foxconn needs to add a 200 setting to their Memory Speed settings. This may or may not allow 4 DS DIMMs to run at DDR400 speed, but it would allow us to determine whether the board could support 4 DS DIMMs at DDR400. For now, consider this board limited to DDR333 with 4 DS DIMMs.
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ChineseDemocracyGNR - Tuesday, December 28, 2004 - link
The SiS755FX adds 1000MHz HTT support. So it's a chipset for socket 939 processors.The SiS756 is a new chipset, supporting PCI-E graphics.
RAINFIRE - Sunday, December 26, 2004 - link
I wasn just wondering if the SiS 756 is replacing the 755FX chipset. This seems to be the case with me. Anyone know if this is what is happening?RAINFIRE - Sunday, December 26, 2004 - link
I was just wondering if the SiS 756 chip is better/replacing the 755FX. This seems to be the case as far as I can see. Any thoughts, conments on that? I've been keeping a Next Gen Motherboard list and want to get it right.Cygni - Sunday, December 19, 2004 - link
The 755 had solid performance and i was very surprised that more board makers didnt use it. The 755FX/756 seems to be another step in that direction. Realistically, because the Nforce4 and ATI Xpress 200 are STILL not on the market, it is still possible for the 756 to be the first PCI-Ex capable AMD chipset.ChineseDemocracyGNR - Friday, December 17, 2004 - link
Yes, the board is available here:http://www.newegg.com/app/ViewProductDesc.asp?desc...
Price is $101. The Foxconn is $69, the ASRock is $77 but it has overclocking options (the Gigabyte doesn't).
Peter - Friday, December 17, 2004 - link
I've seen that ... they did actually go ahead and made it available WITH the dedicated VGA RAM? Good then. But at $30 more than the same thing in shared-RAM configuration, they've missed the price point ... I mean, $30 buys me an entire Xabre graphics card.ChineseDemocracyGNR - Friday, December 17, 2004 - link
#20, that is great news! Are you going to test the K8Upgrade-760GX (SiS760GX, mATX) or the K8Upgrade-1689 (ULI M1689, ATX)?#22, Gigabyte makes a board with dedicated memory. It does improve performance but it's considerably more expensive too (at least $30).
There's a review:
http://www.ocworkbench.com/2004/gigabyte/K8S760M/K...
Peter - Friday, December 17, 2004 - link
Wesley, I wrote this _after_ reading the article ;) Head still on shoulders.SiS integrated video for the A64 platform looks particularly interesting because it can have dedicated (!) VGA RAM attached to the north bridge chip. This is because they left the RAM controller in there - exclusively for the integrated VGA this time, since the CPU brings its own.
Now if only the board makers adopted that feature ... all I've seen so far (ASRock, ECS, PC-Chips) run it in shared-RAM mode, and so does my shiny new Averatec 5500 notebook. History repeating - even back in the Pentium and early PII days, the integrated SiS chipsets (530, 620, 630) supported dedicated VGA RAM, but practically nobody made boards that used it.
As for clock synthesizer chips, well if this piece of hardware doesn't support what you want it to do, then no update of BIOS or other software will make it.
Calin - Friday, December 17, 2004 - link
#17, I would like to have an Athlon64 board with integrated video... but not with SiS integrated video. I would wait until (hopefully) some ATI-based board appears here in Romania. (I know I might be wrong about not buying a SIS with integrated video, but I prefer not to take the chance)Calin
Wesley Fink - Thursday, December 16, 2004 - link
#17 - We have been talking with Asrock, and we will be reviewing a ASRock K8Upgrade, and the upgrade module, which is based on the SiS 760GX. We also requested a ULI chipset board but we have not received any info yet on when that board may be available for review.