Vrm

[davmax]

I am a little confused with the use of VRM in this forum. I thought it stood for Voltage Regulation Module for the CPU power supply yet I see applied to the MOSFET switches used in the circuit. Could we have a definition please.

I have seen a request to define the MOSFET terminals. Control is via the Gate, the input signal is applied across the gate and source. The Source and Drain pass the main switching current. Depending on circuit configuration the Drain will be the supply and the Source the output, or this is reversed with a supply polarity change. For N channel MOSFETs the Drain is positive. For P channel MOSFETs the Drain is negative.

Hope this is clear.

[linuxguru]

Re: Vrm

VRM refers to the entire subsystem, including controller, caps, inductors, diodes, FETs, etc. It used to be on a removable module, but is now usually integrated into the motherboard layout. The older system was more modular and flexible - for instance, on my HP Kayak, which originally shipped with a Klamath PII 233, it was possible to upgrade all the way to a Coppermine 1.1 Ghz merely by changing the VRM and upgrading the BIOS.

[Per Hansson]

Re: Vrm

This would be a VRM, on it are Mosfets and Capacitors... However when speaking of the VRM on a mainboard that does not feature a "Voltage Regulation Module" but instead everything integrated it is still the same parts talked about, i.e. the Mosfets and Capacitors used for filtering current and reducing or increasing the voltage for whatever device needing it, most commonly the CPU but also memory and add in cards...

[davmax]

Re: Vrm

Thanks for confirming what I thought it is. Great

[Topcat]

Re: Vrm

last time I actually saw a "VRM' as a module, it was a dual P-Pro board, about in 1998.

I suppose the politically correct term for an integrated VRM would be 'voltage regulator circuit', since they are no longer 'modules'. However, when you mention VRM, any half-ass tech will know what you're referring to. The voltage regulator circuit or module consists of the FET's, the regulator itself, and all other supporting components.

[gg1978]

Re: Vrm

Actually, in later Intel documentation, they have two "options" for putting the VRM on a motherboard. The VRM module , as stated above, can be a discrete component that is socketed, for easy replacement, although this is very uncommon nowadays for desktop equipment. Servers, on the other hand, are much more likely to have VRM Modules.

Newer Intel documentation calls a VRM that's soldered down to the motherboard the "VR Down" option, though for most stuff, it's just the way it's built, no real "option" there, unless you're designing the motherboard.


I remember a Gigabyte board that had a 3 phase VRM soldered down to the board, and it had a socket to add a proprietary 3 phase VRM module, to yield 6 phases. My Gigabyte Athlon 64 motherboard has a 6 phase VRM already, no need for an addon VRM module to add 3 more phases.

[gg1978]

Re: Vrm

Also, on a side note, the latest desktop board i've seen that had a discrete VRM module was a Dell Dimension 8100. IIRC, it had the 50 pin variety of VRM module that is the latest spec. Had this funny little wire clip thing to make sure it stayed in its socket. Also, the Quad Xeon server at work has the 40 pin variety of VRM's on it.

[Topcat]

Re: Vrm

Also, on a side note, the latest desktop board i've seen that had a discrete VRM module was a Dell Dimension 8100. IIRC, it had the 50 pin variety of VRM module that is the latest spec. Had this funny little wire clip thing to make sure it stayed in its socket. Also, the Quad Xeon server at work has the 40 pin variety of VRM's on it.

MMMMM QUAD XEON!
PICS NOW!

I'm assuming its an old P2/P3 slice of bread sized xeons... P4 Xeon boards are RARE and expensive.... I drooled over Tyan's a few times.

[gg1978]

Re: Vrm

The board at work is an Intel SRKA4 "package".. Can take up to 16G of PC100 Reg. ECC SDRAM. I hate to think how much the company paid for the beast back in 2000/2001.


http://www.intel.com/cd/channel/rese...iefs/36119.htm


Of course it has Sanyo Os-Con's on it also..

[Rainbow]

Re: Vrm

VRM sockets are common on older Socket 7 boards. On these boards, you can run single-voltage CPUs (non-MMX Pentium, AMD K5, non-L&non-MX Cyrix 6x86 and IDT Winchip) without the VRM. For dual-voltage CPUs, you need to install the VRM. I've seen the VRM socket on many boards but I've never seen the VRM module itself - so they must be pretty rare.

[linuxguru]

Re: Vrm

AFAIK, the Socket-7 VRMs had the same pinout as the first-generation PII VRMs. Perhaps some of the VID codes below 2V were not yet defined or reserved, but you could use a PII VRM on a Socket-7 MMX board, IIRC.

[Per Hansson]

Re: Vrm

last time I actually saw a "VRM' as a module, it was a dual P-Pro board, about in 1998.

Yea, the pic of the VRM I posted was from a Proliant 800 dual PPro 200mhz Socket 8 server...

I've got two such servers, but only three processors... So if anyone happen to sit on a VRM and a 200mhz 256kb SL22T CPU that would fit this system I would be happy to take it off your hands... Of course it could use some more memory too, only two 32mb ECC 168 pin unbuffered DIMM's in it now...

[Per Hansson]

Re: Vrm

More VRM goodness, this one from a Dual PPro 333mhz Proliant 3000 server, showing the whole processor board, processor and VRM... Dunno what type of caps are on the left side of the VRM, they just have an "M" for their name...

[linuxguru]

Re: Vrm

Panasonic, with the T-vent. 'M' for Matsushita, owner of the Panasonic brand.

[Per Hansson]

Re: Vrm

Thnx man... Was just curious what they where because I know they would be high quality since that is all that I expect from Proliant servers... This quote from the good caps thread:

Panasonic FC. Note the T vent marking which is exclusive to panasonic. Note the M character in a box which indicates Matsushita the parent company of the panasonic brand. Note the navy colour, they also come in black, note the gold negative stripe which is on both colours. Note the FC after the +105oC which indicates they are FC range. There is also FA series which is better but FC series is excellent for motherboard applications and general availability is good.