PMCS (MM)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Item 1.

Security and Issuer

This Schedule 13D/A constitutes the first amendment to the Schedule 13D originally filed by the Reporting Persons with the Securities and Exchange Commission (the “ SEC ”) on January 17, 2012 (the “ Statement ”) with respect to the common stock, $0.001 par value (the “ Shares ”), of PMC-Sierra, Inc. (the “ Issuer ” or the “ Company ”). Except as specifically amended by this Schedule 13D/A, the Statement remains in full force and effect.

Item 2.

Identity and Background

This Statement is being filed by Relational Investors Mid-Cap Fund I, L.P. (“ MC I ”) and Relational Investors Mid-Cap Fund II, L.P. (“ MC II ”), collectively, the “ Relational LPs .” Each of the Relational LPs is a Delaware limited partnership. The principal business of each is securities investment.

This Statement is also being filed by Relational Investors, LLC (“ RILLC ”), a Delaware limited liability company. The principal business of RILLC is being the sole general partner or sole managing member of the general partner of certain investment partnerships, including the Relational LPs and the investment adviser of certain client managed accounts, the “ Managed Accounts ”. The Relational LPs and the Managed Accounts are the beneficial owners of the securities covered by this Statement. Pursuant to the Limited Partnership Agreement of each of the Relational LPs, and the investment management agreement of the Managed Accounts, RILLC has sole investment discretion and voting authority with respect to the securities covered by this Statement.

This Statement is also being filed by Ralph V. Whitworth and David H. Batchelder. Messrs. Whitworth and Batchelder are the Principals of RILLC, in which capacity they share voting control and dispositive power over certain securities covered by this Statement. As such, Messrs. Whitworth and Batchelder may be deemed to have indirect beneficial ownership of such securities, but, each of Mr. Whitworth and Mr. Batchelder disclaim beneficial ownership of the Shares except to the extent of his pecuniary interest therein. The present principal occupation of each of Messrs. Whitworth and Batchelder is serving as Principals of RILLC (Messrs. Whitworth and Batchelder, together with Relational LPs and RILLC, hereinafter, the “ Reporting Persons ”).

During the last five years, none of the Reporting Persons has been (i) convicted in a criminal proceeding (excluding traffic violations and similar misdemeanors) or (ii) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction, and as a result of such proceeding, was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

The business address of each of the Reporting Persons is 12400 High Bluff Drive, Suite 600, San Diego, CA 92130.

Messrs. Whitworth and Batchelder are citizens of the United States.

Item 3.

Source and Amount of Funds or Other Consideration

The Reporting Persons purchased an aggregate of 17,847,255 Shares for total consideration (including brokerage commissions) of $119.6 million derived from their working capital.

Item 5.

Interest in Securities of the Issuer

(a)           As of the date of this Statement, the Reporting Persons beneficially own in the aggregate 17,847,255 Shares, constituting approximately 8.88% of the outstanding Shares.  The percentage of Shares owned is based upon 200,886,703 Shares reported to be outstanding on November 5, 2012, as set forth in the Issuer’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2012.  The Reporting Persons may be deemed to have direct beneficial ownership of the Shares as follows:

NAME

NUMBER OF SHARES

% OF OUTSTANDING SHARES

VOTING AND DISPOSITIVE POWER

RILLC

1,351,978

0.67%

Sole

MC I

11,311,919

5.63%

Sole

MC II

5,183,358

2.58%

Sole

RILLC, individually and in its capacity as an investment adviser, may be deemed to possess direct beneficial ownership of the 1,351,978 Shares that are owned by it and the Managed Accounts. Additionally, RILLC, as the sole general partner, of each of Relational LPs may be deemed to beneficially own (as that term is defined in Rule 13d-3 under the Securities Exchange Act of 1934, as amended) the 16,495,277 Shares beneficially owned by the Relational LPs because the limited partnership agreements of the Relational LPs specify that RILLC has sole investment discretion and voting authority with respect to those Shares.

Each of Messrs. Whitworth and Batchelder, as Principals of RILLC, may be deemed to share indirect beneficial ownership of the Shares which RILLC may beneficially own.  Each of Messrs. Whitworth and Batchelder disclaims beneficial ownership of such Shares except to the extent of his pecuniary interest therein.

To the best of the knowledge of each of the Reporting Persons, other than as set forth above, none of the persons named in Item 2 is the beneficial owner of any Shares.

(b)           See item (a) above.

(c)           Not applicable.

(d)           No other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares covered by this Statement, except that dividends from, and proceeds from the sale of, the Shares held by accounts managed by RILLC may be delivered to such accounts.

(e)           Not applicable.

By:

RELATIONAL INVESTORS, LLC

as general partner to each,

By:

/s/ Ralph V. Whitworth

Ralph V. Whitworth, Principal

RELATIONAL INVESTORS, LLC

By:

/s/ Ralph V. Whitworth

Ralph V. Whitworth, Principal

/s/ Ralph V. Whitworth

Ralph V. Whitworth

/s/ David H. Batchelder

David H. Batchelder