www.cpu-central.com/dualceleron -> www.clickoncpu.com/articles.asp?article_id=6879&decor_int=1
This makes it a very low cost CPU pefect for low cost systems. The Celeron is probably one of the most overclockable CPUs available today. It has been confirmed by multiple sources that a 266MHz Celeron can run at 448MHz without any stability issues. This is because of the fact that the Celeron has no L2 cache - on a Pentium II, as you increase the core speed, the speed of the L2 cache increases, and the L2 cache was not designed to operate at such high speeds. However, on a Celeron, there is no L2 cache to hold the CPU back. The Pentuim II, as we all know, can be run in a dual CPU configuration. Since the CPU core of Celeron is the same as Pentuim II, I thought that I could use this good cost/performance CPU in a dual configuration. The Problem with "Dualization" The first problem when we try to use Celeron in a dual configuration is that on the Celeron, BR1# is not connected from the CPU core to CPU board. That signal line is necessary for the CPU to operate in a dual configuration. Through further invesitgation of a datasheet on Intel's web page, the pin assignment of the Celeron is the same as the Pentium II except 66#/100#, which decides the base clock. By connecting the BR1# signal line to the land of B75 on the CPU card edge, we can assume that the Celeron may operate in a dual configuration. Getting the Components Now that we have a goal, we went out and purchased a dual Slot 1 motherboard, and two Celerons (retail package SL2QG). The 1st one I bought in the middle of May, and the second I bought at the beginning of June. The 1st one was produced 5/1/98, and the 2nd one was produced 5/15/98. Fortunately, both Celerons can operate easily at 412MHz. Before Alteration Before altering the processors, I installed the 2 Celerons in the motherboard and turned the power on. The result was negative: the computer did not even POST. Using this wire we connected BR1# in the CPU core to B75 on the board. Now with the narrower wire we reconnect the CPU core and board. There is no break or sliding out when the Celeron is installed into the slot. If just a little slip happens, the wire could stick to the next land (which could cause serious problems). To prevent this, we cover the area around B75 with masking tape. The 2nd Celeron is then altered the same way as the first. Now try Dual mode After making sure that the altered Celerons do not have any problems, we now try dual operation. We rechecked the wiring of the altered Celeron, and there seemed to be no problem. The wire does not short to other lines, and the contact looks right. So, we boot again with one Celeron, and there's still no problem. Just to test, we removed the wire from only one Celeron, and booted dual again. The joy is short-lived however, as the motherboard only recognizes a single processor. The voltage of BR0#/BR1# Next, we checked the voltage of BR1# while the Celeron was operating. Though this voltage looks a little high, we cannot check the pattern from the surface of the board to BR1#, I suppose the voltage of this pin may be increased in the middle of the board. For some time we traced the pattern of the Celeron board, and measured the voltage at various points, but we couldn't find a good idea. After shaving we removed the waste by using an air duster or something similar. We reinstalled the altered Celeron to the motherboard for confirmation. But with the above alteration, the Celeron will not work as a dual CPU. According to the data sheet of the Pentium II, BR1# is GTL+Input. Lastly, we carefully checked the jumper line for a short or lose solders. Now Check Operation Now, we insert both Celerons and power on the system. If the system will not boot here, or the system recognizes only 1 processor, you may need to recheck the wiring. Perhaps the wire is worn or was pulled out of the connector in the slot. When even a single processor does not boot, the Celeron may not be correctly installed in the slot. This alternation is dangerous and it could physically destroy your CPU. If you try to do this alteration, you're own your own - ClickOn-CPU bears no responsibility for any damage caused to your CPU. Success Stories People have reported successfully running Dual Celeron setups on the following motherboards (with CPU speeds ranging from 266MHz to 448MHz): * TYAN S1696DLUA Thunder 2 ATX * ASUS P2B-D * Gigabyte GA-6BXD * ASUS P2B-DS * MS-6120 * SuperMicro P6DGE * Soltek SL-68A * Tyan S1832DL Many people have also been able to run a Pentium II along with a Celeron in a Dual Processor motherboard - stay tuned to ClickOn-CPU for more information on this.
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