- So far any 65nm or 45nm FSB800 CPUs should work without any hardware mods, though for 45nm CPUs you may need to include additional microcodes if your CPUID is not 10676 which the stock BIOS has.
- As stock BIOS has only microcodes for CPUID 10676h, you may want to add additional microcodes (10677h and 1067Ah) into the BIOS, and preferably updated ones for all Core 2 CPUs, to maximize support of functionality.
- FSB800 Core 2 CPUs may drop to 100MHz bus speed in some circumstances. The reason behind the reduction of bus speed appears more complicated than I originally assumed, as there are other circumstances in which the CPU does operate at intended bus speed.
- FSB1066 and FSB1333 Core 2 Duo CPUs can work, but they will only operate at FSB400 without hardware mods.
- Not sure about Core 2 Quad CPUs as I haven't succeeded in booting one. There were reports of that some C2Q may boot but only 2 cores will be usable.
- If you're using X6800, be noted that the CPU multiplier setting is flawed that it would actually set the CPU to use the maximum possible value (about 60x) which obviously cannot work, then switches to a fail-safe saying overclocking failed and lets you set the correct/desired multiplier.
- If using 45nm CPUs with CPUID 1067A, you may experience issues with ACPI shutdown, that after pressing POWER button, or issuing shutdown from operating system, the system will hang, requiring holding POWER button for 5 seconds to shut down. A new BIOS version 865GV00C apparently fixed the issue and you can correctly shut down the system with that BIOS version. (Many thanks to dm- for providing a copy of 865GV00C BIOS).

- You may need to set memory frequency to 266MHz when using a CPU with 266MHz bus speed (FSB1066).
- For 200MHz (FSB800) CPUs, any memory frequency can be used.
- The board can be very picky when it comes to memory. Some combinations work but not reliable, would end up running at an undesired 3-4-4-12 timing and/or report errors. You may need some efforts to get the right combinations that would work at desired timing as well as getting no errors during tests. (Manually specify DRAM timings instead of SPD may not always work)
- Can't be sure about this board's RAM slot quality. It's entirely possible to have faulty slots which will lead to unstable system as well as the inability to utilize dual-channel configurations.
- When using only onboard GPU, you can get up to 3800MB of RAM. However, it seems video cards including PCI ones may additionally map certain areas in the system arena to their liking, further reducing available RAM. In my case with a half-height PCIe video card (AMD) with a PCI-PCIe bridge, I ended up with only 3166MB of RAM available (with onboard graphics set to disabled, or it will be minus the shared memory specified).

Considering there are different revisions of this board as well as different hardware configurations the BIOS options are a bit messy.
Actually all board variants (1.0s1.2, 1.0s1.3, etc.) share the same BIOS. Some features are only visible on specific board variants.

- In CPU configuration sections some NetBurst-specific options are visible to Core 2 CPUs. I think it's advised to configure the options appropriately depending on the CPU architecture to ensure system stability.
- The Hyper-Threading switch actually controls the availability of the second core for Pentium D CPUs. If set to disabled, the second CPU core would not be available. It has no effect for Core 2 CPUs.
- Onboard GPU cannot be fully disabled with 1.0s1.3 revision (865GV), as well as with 1.0s1.2 (865G) when using only a PCI video card. It remains visible to the system even when you set it to Disabled. That option only prevents the BIOS from reserving memory for it.
- Boot Video card init order will show AGP related options for 1.0s1.2 board (865G). For 1.0s1.3 boards (865GV) only PCI options will be provided.
- Enabling "Memory Hole" will actually limit available system memory to 15MB (at least from what BIOS reports). Not desirable for other use cases, but it can be useful for DOS programs that would misbehave when the system has a lot of installed RAM.
- USB boot is supported, but you have to modify BIOS hard disk order in order to do so. Should be noted that you must make sure the BIOS_WP1 jumper (near the BIOS chip) is not shorted (which write-protects the BIOS. The manual I could find online was wrong and suggested the opposite) to be able to actually make changes to boot priority as these parts are stored in NVRAM (an area inside BIOS chip).*
- There's an option called "C.S.A Gigabit Ethernet" that I'm not sure about the actual function. Most likely it's a toggle to enable the 1Gbe interface on board variants that actually equipped it. I don't think my boards have it...

* It seems the 865GV00C BIOS had revised this part now that all hard disks can be accessed from boot menu instead of just the topmost one, so changing hard disk order is not needed there.

No, AGP cards cannot be used on 1.0s1.3 boards even if you solder an AGP slot on it, as they use 865GV. If you do have such a slot it may be possible to use the so-called ADD card which enables you to use DVI with the onboard graphics, but I haven't seen such a card myself, so I cannot be entirely sure about this.

My 1.0s1.3 board comes with such a slot but as far as I've tested, it's not usable. You can only use AGP cards with 1.0s1.2 boards, but only half-length ones, since full-length cards will get in the way with the memory slots.

For both 1.0s1.2 and 1.0s1.3, when using a PCI video card, the onboard video controller will remain present on the system, just they don't claim VGA resources. Be sure to disable Intel graphics driver whenever possible (for Windows, Linux, etc.), as the system may attempt to initialize the onboard video controller whenever possible, which may lead to undesired consequences. Onboard video controller can only be disabled on 1.0s1.2 if and only if an AGP video card is present on the system.

The BIOS incorrectly sets all ISA DMA channels to the LPC interface, with no convenient way to toggle the ones used by ISA cards to PC/PCI. As such, while the card can be detected and configured (including via ISA PnP), DMA operations will not work unless you manually change the respective DMA channels to PC/PCI.

You can refer to ICH5 datasheet and modify the bits in registers 90-91h of the ISA interface (Device 1Fh, Function 0) to make the channels you need accessible to PC/PCI, but do not change all of them. You need to keep the DMA channels used by SuperIO on LPC, namely FDC and ECP Parallel Port, or you'll break the functionality.

This is an interesting board, using a soldered ER14250 battery (3.6V) instead of the usual replaceable CR2032 coin cells. Since it's soldered to the board, it is difficult to replace should it have been drained, although 14250 battery is supposed to hold much more capacity than coin cells thus last longer.

If you're skilled enough, it is possible to solder a battery holder in its place for easier access/replacement of the battery, but keep in mind that the battery holder will be a bit larger in size than the actual battery and you may get in the way of other components, namely the IDE1 connector as well as the BIOS chip socket.

On the board I'm currently using, I experimented with a USB-rechargeable 14250 battery after soldering a battery holder, and it turned out to be working fine, despite the battery, rated 3.7V, emits ~4.1V when fully charged. Not sure whether my board's VBAT sensor was broken (as it showed very low values like +0.032V), but CMOS data is indeed being preserved.

* Theoretically you don't really have to use a 14250 battery for the CMOS/RTC part, considering the size of a 14250 battery holder. You can pretty much install anything that could provide a reasonable +3V there.
** If you're using a USB-rechargeable battery (that has a USB connector for charging input), you can pretty much "plug" the battery into one of the board's USB front panel header so you don't ever have to worry anymore, as it'll automatically gets charged so long as you keep the system plugged in. Just that it may have an impact on the battery's lifespan to some extent.

CF card by default assumes Secondary Master and unlike other motherboards such as IMB200 there's no way to toggle it. Should note that like the BIOS_WP function, the info in the manual was wrong and in reality what the board does is actually the opposite!

As such, if you use a IDE44-SATA adapter to connect SATA drives to the IDE-SLIM port you need to do some hardware mods, and how it is done depending on the adapter PCB you use (mSATA-IDE44 also counts):
- Force the disk to IDE Slave. Some PCBs have jumper or footprint for such a toggle that you can just use it. In JM20330's case, if unsure, you can use a multimeter to inspect where you can access pin 33 (MSSEL). If this is not properly configured and the disk operates as Master, it will prevent installed CF card from working.
- "Cheat" 80-wire detection. In order to allow higher UDMA levels the pin 34 (PDIAG) must be grounded. A simple way to do is connect pin 30 and 34 with a wire. This is very important, as if 80-wire detection is not correctly configured, even the CF card will be forced to UDMA2. Additionally, 80-wire detection must be set to "Host" in BIOS to ensure everything works correctly.

FSB800 Core 2 CPUs will work as intended, but those with higher FSB such as FSB1066 and FSB1333 will only work at FSB400. Additionally, when operating at FSB400, only 266MHz and Auto options in the memory frequency settings will work. Other settings will make BIOS fail to POST requiring a reset.

BIOS will always report the official CPU clock and FSB instead of the real ones. You need a system information tool like ASTRA or HWINFO to find out what clock/FSB your CPU is actually running at.

Further digging into the datasheet of 865G(V) northbridge I found some interesting information:
- 865G(V) only cares about BSEL1 and BSEL0. BSEL2 is not involved (and that was the only difference between FSB1066 and FSB1333).
- When BSEL1:0 passed to the northbridge is 00b, which is the case for both FSB1066 and FSB1333 C2D CPUs, the northbridge operates at 400MHz FSB.

(Same applies to 865P and 865PE, except 865P does not support FSB800, only FSB533.)

As such, FSB1066/FSB1333 C2D CPUs operating at FSB400 with 865G/PE northbridges is intended behavior. The same BSEL setting table can be confirmed from P4 Northwood (Socket 478) datasheet as well.

BSEL2 was introduced with LGA775 packaging. Socket 478 CPUs have only BSEL1:0. Considering 865 family northbridges targeted both S478 and LGA775, this behavior is expected.

It is possible to alter the BSEL value passed to the northbridge with a hardware mod on this board. Original credits to this Modlabs post.

After this mod, memory clock on Auto setting becomes 400MHz, and ASTRA now reports the CPU running at 200MHz bus speed (FSB800), which is definitely better than leaving it running at FSB400. A side effect is that this will break the use of any FSB533 CPU, which mostly concerns old P4 models.

This leaves only the question whether it's possible to somehow reprogram the clock generators later on to get the desired FSB. The board uses the following PLLs:
- 1.0s1.2 board: CY28405OXC. This one has only values between 100-200MHz bus speeds.
- 1.0s1.3 board: W83194BG-603. This one has some values for 266MHz and 400MHz bus speeds, just no 333MHz ones.

Apparently W83194BG-603 uses the same FS4:0 to clock value table compared to W83194BG-SD which Conroe865PE uses, but with a good portion of it reserved (particularly the 333MHz ones). However, 603 is not interchangeable with SD (and also 619) due to different pin layouts. Don't know if there are any other compatible clock generator models that have better options.

A while ago I got myself an ANOVO AIMB-865 (V1.0S1.2, 865G with 1 ethernet controller placed around the lower two USB ports) intended to replace an Axiomtek IMB200 mainly for better CPU support (that board supports only up to Pentium D 960 as the official manual stated, and any attempt to extend the CPU support past it, mainly by adding microcodes and such, was not successful), yet I've found quite a few problems with the new board.

1. The board officially claims to support Core 2 Duo up to 2.66GHz, and as tested, up to Core 2 Extreme X6800 can boot. While the BIOS shows correct clock values (so does Windows XP's System Information, which doesn't seem to reflect actual values, either), the actual system bus speed is only 100MHz, regardless of whether it is FSB 800 (200MHz) or FSB 1066 (266MHz). Also, when using a FSB 1066 Core 2 Duo, the board can only boot when memory speed is set to 266MHz (while a FSB 800 Core 2 Duo can boot with any option, 266/333/400 MHz, despite in both scenarios, the CPUs will have an actual system bus speed of 100MHz).
2. The board seems to have issues handling the multipliers when booting with an extreme edition CPU, as it initially sets the multi to the maximum value (60x I think) then boots with an overclock failed message and has to manually set the multi back to the intended value in order to be able to boot properly during subsequent boots.
3. Somehow the AIMB-865 board I have fails to boot on any valid dual-channel memory configuration regardless of installed CPU. Using single-channel memory configurations (by leaving one of the slots empty, or using memory sticks of different sizes), however, will boot properly.
4. Tried a Pentium D 965 and it could not boot at all. Perhaps a BSEL mod that sets to 200MHz bus speed (which somehow had no effect on IMB200) is needed, but I haven't had time to try it there.
5. The ISA DMA does not work out of box. As tested, a chipset register hack similar to the one in this video is required for ISA DMA to function, and it only lasts for this boot instance only (PS: Setting the register values involved to exactly the ones shown in the video actually caused a hard freeze during my initial tests after playing some ISA sounds, as I might have flipped some other register bits that I shouldn't have. Doing it by figuring out which bits the actions actually flipped according to the video, however, I did not encounter freezes anymore).

The only detailed information about the board I could find is this one (from Modlabs, in Russian), and it appears to have mentioned some of the problems I'm having (namely the ISA DMA and the actual system bus speed issues). Besides, there is an official BIOS image named 865GV008.ROM which bears the same BIOS version number of the board I currently own, but I cannot confirm whichever variant the BIOS was intended to (or is not specific to variants), as there is also another major variant called V1.0S1.3 which is 865GV-based and lacked the AGP slot.

Apparently regarding the 100MHz system bus issue when running Core 2 CPUs on 865-based mainboards, there's already a post talking about it in an attempt to get it working on a different board than this one. And I'm not certain if there are any methods other than BSEL mod, to force 200MHz bus speed for Pentium D 965, if the motherboard itself is not (or not entirely) using BSEL to determine CPU clocks (like my IMB200, the BIOS always gives it a 33MHz system bus for Pentium D 965 then hangs, even after doing a BSEL mod that has been confirmed working using another 865GV-based board I had for reference, MSI 865GVM3-V).

Besides, from the Modlabs post I did not see it mentioning the inability to boot when using dual-channel memory configurations, so whether this is due to the board's BIOS or my board itself (hardware issue) could not be determined.

So again, there are still a lot of things needed in order to make AIMB-865 useful, so I'll have to stay with IMB200. Compared to AIMB-865, while it lacks the potential to extend CPU support (for better forward compatibility), and it doesn't have an easy way to manage USB boots (so I have to install OSes using optical discs instead), it has out-of-box ISA support (including ISA PnP like AWE64 Gold).

LATE EDIT (2023-06-05): The video I referenced is long gone so I removed the dead link. I don't know if anyone has ever re-upped the video, or has any documentation that could be made public so it could be put there for reference.