Finally my samples of OCZ Dual Channel Gold4000 in 1GB-kit (2x512MB) arrived (thank you OCZ). They did very well. I immediately threw caution to the wind and set the Epox to 270fSB, 1:1 using 2.9VDIMM. It posted, ran, and benchmarked all day. Then I decided to go higher, and the OCZ Gold4000 ran at an amazing 276FSB (1:1 Ratio / 2.9VDIMM / SPD). The GolD4000 performed quite well considering its higher latency SPD, over 6100MB/s, bandwidth! I only wish I could get the Corsair to run higher.
Of all the motherboards mentioned here, the Epox has the best (stock) overclocking potential due to its higher voltages. Unfortunately, of all three motherboards the Epox also has the worst time with newer memory. When attempting to use any divider other then 1:1, the same anomalies occur with the OCZ GolD3700/4000 memory especially in 512MB stick form, or the Corsair Twin-X4000 in 512MB/256MB sticks, with slight variances. For example, if using the Corsair Twin-X4000 in 256MB sticks in DC, Epox BIOS can be re-set in jumper less? Yet in 90% of the cases where memory dividers or excessive FSB speeds are attempted, BIOS values can only be reset by pulling the plug, replacing the newer with older DDR, re-set BIOS values, enter Window's, and power down from the OS. I even tried to circumvent this tedious power-down process, attempting to use the power-button in pre-Post DOS mode. After switching the OCZ GolD3700 out, and putting GolD4000 (512MB sticks) back in, I realized this method doesn't work either.
One must enter the Windows OS system and power-down from it. If things weren't bad enough, this problem isn't localized to the use of Memory Dividers. When higher FSB speeds are attempted in 1:1 ratio, 90% of the time, one must employ the arduous method detailed above. At this point I realize it's not Corsair memory (of which I was never really convinced anyway), OCZ memory, nor do I believe it to be a specific motherboard related problem. Perhaps it's simply an amalgamation of certain conditions, and/or some anomaly in the 875's NB-MCH. And I'm not the only person experiencing these anomalies. Here's a few posts from Corsair and Abit's end-user assistance forums e.g; HouseOfHelp Fourms
& Abit Forums
Another oddity with the Epox board was no PAT-like memory options were offered in the shipping BIOS. And even after flashing the BIOS (of which there is only one revision) I'd thought PAT was disabled as can be seen below in Sandra screen while overclocking OCZ GolD4000 (1GB-kit);
I'd like to note here the performance with the OCZ GolD4000 Dual Channel series. A speed of 276FSB at 1:1 ratio requiring only 2.9VDIMM, is pretty dam impressive if you ask me! In so far as PAT is concerned, although Sandra is reporting PAT as Disabled, this is a contradiction, because PAT is an innate feature of the 875 north bridge. If for some odd reason it is disabled as Sandra is reporting above, then the bandwidth is even more impressive. In so far as Corsair Twin-X4000 and the Epox, I was only able to attain a 260FSB, which is still very good considering its DDR500. Yet I still believe there's much more potential in the Corsair memory. I believe Epox as well as Abit need to collaborate with Intel on future BIOS revisions. It's highly unlikely Corsair, or motherboard makers will remain complacent around this issue, under enough pressure from end-users.
Abit has been pretty hard at work considering the number of BIOS revision's at their site. I also had better luck overclocking with Corsair's 512MB modules, then their 256MB size? This is most likely attributable to a better pair of modules, then anything else. To summarize, here's my results with these motherboards;1.) Abit IS7-E + Corsair Twin-X4000 (512MB & 256MB modules) in DC/Async all dividers except 1:1 = BIOS Lock-out
2.) Abit IC7-G + Corsair Twin-X4000 (512MB & 256MB modules) in DC/Async all dividers except 1:1 = BIOS Lock-out
3.) Abit IC7-G + OCZ GolD4000 (512MB module) in DC/Async all dividers except 1:1 = BIOS Lock-out
4.) Epox 4PCA3+ using OCZ GolD4000 (512MB module) in DC/Async all dividers excpet 1:1 = BIOS Lock-out
5.) Epox 4PCA3+ using Corsair Twin-X4000 (256MB & 512MB) in DC/Async all dividers except 1:1 = BIOS Lock-out
6.) DC = Dual Channel / Async =(prima facie)
BIOS Lock-out's also occurred when exceeding 265FSb in 1:1 with Corsair, and exceeding 280FSB in 1:1 with OCZ regardless of VDIMM using the Epox 4PCA3+. In so far as Abit's boards, I attempted to ameliorate the issue flashing the BIOS three revision's back to no avail. On a side note, always back-up your shipping BIOS during the Flash process.