Why are SiS motherboards so wimpy?

ahmerali · 2005-12-29, 16:42

Especially for GIMPS...I always thought that the primary factor for GIMPS processing was CPU power and cache. On some systems I see a very marked difference between MBs with SiS chipsets and those with "better" chipsets like Intel and VIA. Now I know that the SiS chipsets are slower overall and that some corners are cut to save money, but it just seems really out of whack...for example, I have two nearly identical machines, one with a VIA chipset and one with SiS. Both are Celeron 2.4 GHz, with 512 Mg RAM. I don't have the exact iteration times in front of me, but I know these machines run 24 hours a day. They are both testing numbers in the 30400000 range. The VIA-based system will finish after about 77 days of testing. The SiS one has been going for 60 days so far and is not due to finish for 90 days?

So far as I can tell there is no usage pattern difference...can anyone explain this?

sdbardwick · 2005-12-29, 18:37

The SIS system probably has a configuration problem. I haven't noticed any significant differences between SIS/VIA/Intel chipsets (comparing single channel or dual channel to like counterparts) in Prime95. Certainly nothing of the magnitude you are experiencing.

Some questions to consider:
Could the SIS system be using integrated video? Is the processor actually running at full speed (FSB set correctly)? Are RAM settings correct (clock speed and timings)? Does the SIS system have an active screensaver (the OpenGL screensavers in particular will kill Prime95 performance)? Is it virus-free?

PhilF · 2005-12-29, 18:37

One explanation might be that the VIA motherboard has a Celeron D 2.4 Ghz. CPU (which has 256K cache) while the SiS motherboard had a Celeron 2.4 Ghz. CPU (which has 128K cache). The 128K cache CPUs are terrible at LL testing with Prime95, even though Prime95 version 24.14 has been optimized as much as possible for a 128K cache.

You can check how much L2 cache Prime95 thinks the processor has by looking under Options --> CPU.

2005-12-29, 16:42	#1
ahmerali Jul 2005 19 Posts	Why are SiS motherboards so wimpy? Especially for GIMPS...I always thought that the primary factor for GIMPS processing was CPU power and cache. On some systems I see a very marked difference between MBs with SiS chipsets and those with "better" chipsets like Intel and VIA. Now I know that the SiS chipsets are slower overall and that some corners are cut to save money, but it just seems really out of whack...for example, I have two nearly identical machines, one with a VIA chipset and one with SiS. Both are Celeron 2.4 GHz, with 512 Mg RAM. I don't have the exact iteration times in front of me, but I know these machines run 24 hours a day. They are both testing numbers in the 30400000 range. The VIA-based system will finish after about 77 days of testing. The SiS one has been going for 60 days so far and is not due to finish for 90 days? So far as I can tell there is no usage pattern difference...can anyone explain this?

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2005-12-29, 18:37	#2
sdbardwick Aug 2002 North San Diego County 5·137 Posts	The SIS system probably has a configuration problem. I haven't noticed any significant differences between SIS/VIA/Intel chipsets (comparing single channel or dual channel to like counterparts) in Prime95. Certainly nothing of the magnitude you are experiencing. Some questions to consider: Could the SIS system be using integrated video? Is the processor actually running at full speed (FSB set correctly)? Are RAM settings correct (clock speed and timings)? Does the SIS system have an active screensaver (the OpenGL screensavers in particular will kill Prime95 performance)? Is it virus-free?

2005-12-29, 18:37	#3
PhilF Feb 2005 Colorado 2²·7·23 Posts	One explanation might be that the VIA motherboard has a Celeron D 2.4 Ghz. CPU (which has 256K cache) while the SiS motherboard had a Celeron 2.4 Ghz. CPU (which has 128K cache). The 128K cache CPUs are terrible at LL testing with Prime95, even though Prime95 version 24.14 has been optimized as much as possible for a 128K cache. You can check how much L2 cache Prime95 thinks the processor has by looking under Options --> CPU.