VIA K8T800 PRO: PCI/AGP Lock and 1000 HyperTransport for Athlon 64
by Wesley Fink on May 6, 2004 5:00 AM EST- Posted in
- CPUs
When the Opteron was introduced about a year ago, VIA and nVidia began their battle for the best chipset and motherboards for the AMD Athlon 64. It appeared early on that despite the lower 600 HyperTransport, the nVidia nF3-150 just might win the first round with a PCI/AGP lock, which was missing from the otherwise superior VIA K8T800 chipset. On Socket 754 single-channel boards, nF3 and K8T800 were basically a toss-up in performance, but K8T800 definitely was the better performer on the Socket 940 Dual-Channel platform. Later, when we discovered that the PCI/AGP lock also did not work on most nF3-150 boards, the supposed advantage for nVidia disappeared.
Recently, there have been many changes in the chipsets available for the Athlon 64 family as manufacturers are gearing up for round 2 - the Socket 939 wars. nVidia introduced their upgraded nFoce3-250Gb chipset with 1000HT, working PCI/AGP locks, and a feature set that finally was competitive with the excellent VIA K8T800, or perhaps even better. The K8T800 PRO is VIA's answer as they also gear up for Socket 939. Based on the excellent K8T800 core, the PRO version finally adds a PCI/AGP lock to the VIA features, and HyperTransport is raised to the new 1000 speed that we will see in AMD Athlon 64 Socket 939 processors.
VIA will price the new PRO chipset version exactly the same as the previous non-PRO version. This means that you will quickly see the K8T800 PRO replace the K8T800 in every Athlon 64 configuration - Socket 754, Socket 940, and the new Socket 939. The chipset will be the same in all configurations, meaning 1000 HT and PCI/AGP lock will soon be available even in Socket 754 boards for current Athlon 64 chips that are based on the K8T800 PRO chipset.
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Odeen - Saturday, May 8, 2004 - link
#4: The answer is pretty much a "yes"Reason: Firewire, in this design, sits on the PCI bus. Gigabit networking sits on the PCI bus. Any soundcard / chip better than chipset-provided onboard sound sits on the PCI bus. Any additional hard drive controllers sit on the PCI bus.
On non-server motherboards, the PCI bus runs at 33mhz and is 32 bits wide, for 133 megabytes/sec of bandwidth
Firewire is 400mbit/sec per port. The new design is 800mbit/sec. This means you will use a maximum of 50 megabytes/sec for a firewire/400 port (granted, the practical peak is less than 50mb/sec, but you'll never eke out 133mb/sec out of the PCI bus either). Add to that the 250mb/sec full-duplex Gigabit Ethernet can generate, and 150mb/sec for ever SATA port courtesy of those Silicon Image chips, and you can see that you're starved for bandwidth.
On the other hand, there's a tidy 533 megabytes/sec of bandwidth between the northbridge and the southbridge.. that means everything that runs straight off the southbridge can report back to the northbridge and, consequently, to the CPU at 533mb/sec. Subtract 133mb/sec for the PCI, and you still have 400 megabytes for LAN and hard drives and firewire, if it's implemented in the southbridge.
Unfortunately, the only true "onboard" firewire comes courtesy of the MCP-T southbridge on nForce2 boards. Everyone else (All Via, all SiS, all Intel chipsets, and all chipsets for Athlon64) has to use a PCI firewire chip.
Pumpkinierre - Friday, May 7, 2004 - link
Welsey #11, I would liked to have seen an 8or9 x 233and234. I still smell a rat. I've run some mobos at 41MHz PCI speed in the past while others (same brand and chipset but different review) would not function. The fact that other posts claim that ABIT have left out the AGP/PCI lock feature of this chipset adds to my suspicion.Klaasman - Friday, May 7, 2004 - link
Why oh why ABIT, would they leave this out?? Damn it!blup - Friday, May 7, 2004 - link
This board breaks my heart. I was hoping for a "BH7 for Athlon 64" i.e. cheap, fast, very overclockable. It is not to be.ABIT has NOT implemented the PCI/AGP lock on this board - maybe there will be a more expensive MAX model that does. Checkout one man's review at http://www.nickgoodall.org/kv8pro/review1.htm
Wesley Fink - Friday, May 7, 2004 - link
#10 -I did a quick check with PC Geiger and the bus was locked on the Reference Board. Since I had the board for only 2 days for testing, there was no time for much more. You will also see I reached 231 overclock on the FX51 at 10 ratio, in addition to the 255x8.
Checking my review notes, I also tested the 10 multiplier at 233 and 234 to determine if there was a ratio drop. I could boot at 233 but the system wasn't completely stable; the CPU simply would not do 234 at standard multiplier. This also suggests a working lock.
Please also keep in mind that VIA has a working pci/agp lock on the PT880 chipset for the P4, so this is not their first PCI/AGP lock. It is just their first lock on an Athlon 64 chipset.
Pumpkinierre - Thursday, May 6, 2004 - link
You got to 8x252 on the Aopen AK86-L (VIA chipset/Skt754) which didnt have PCI/AGP lock but ratio controlled. Given its an a64/FX chipset (and on top VIA) where AGP/PCI lock has been a matter of controversy, would'nt it have been prudent to have used your PCIgeiger to check the PCI frequencies at the different FSB settings-so that we wont be fooled once again!Jeff7181 - Thursday, May 6, 2004 - link
This is definately a good thing... finally overclockers have a choice between chipsets.Warder45 - Thursday, May 6, 2004 - link
I thought the Pro was going to have a HT speed of 1200?Wesley Fink - Thursday, May 6, 2004 - link
#6 -PCI/AGP lock is DEFINITELY working on the Reference Board, but I can not yet address whether Abit has implemented the lock or just dropped the PRO chipset in the older design with no changes. I did see the one review in the UK reporting this issue before the VIA review was finished.
We do have the Abit board coming to us for testing and I will report what I find.
Klaasman - Thursday, May 6, 2004 - link
Abit has a board out now but reports are that it does NOT have the AGP/PCI lock working.