<PAGE>

                                                                   EXHIBIT 10.27

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT
AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
"1933 ACT") OR ANY STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD OR
TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER
THE 1933 ACT AND ANY APPLICABLE STATE SECURITIES LAWS. TRANSFER OF THIS WARRANT
IS FURTHER RESTRICTED AS SET FORTH HEREIN.

                       WARRANT TO PURCHASE 480,513 SHARES
                             OF THE COMMON STOCK OF
                                  EGENERA, INC.

REGISTERED WARRANT NO. HSI-1

EFFECTIVE DATE: FEBRUARY 2, 2004

EXPIRATION DATE: FEBRUARY 2, 2011

      This certifies that HEIDRICK & STRUGGLES, INC. or its transferees or
assigns (each individually, the "HOLDER") for the agreed upon value of $1.00 and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, shall be entitled to purchase from EGENERA, INC., a
Delaware corporation (the "COMPANY"), having its principal place of business at
165 Forest Street, Marlboro, Massachusetts 01752, a maximum of 480,513 fully
paid and nonassessable shares of the Company's Common Stock ("COMMON STOCK") for
cash at a price equal to $2.1622 per share (the "EXERCISE PRICE") at any time,
or from time to time, up to and including 5:00 p.m. Pacific time on the
Expiration Date (or, if earlier, the termination of this Warrant pursuant to
Section 3.3 below), upon the surrender to the Company at its principal place of
business (or at such other location as the Company may advise the Holder in
writing) of this Warrant properly endorsed, a Form of Subscription in
substantially the form attached hereto duly filled in and signed and, as
applicable, upon payment in cash or by certified or bank check or wire transfer
of the aggregate Exercise Price for the number of shares for which this Warrant
is being exercised determined in accordance with the provisions hereof, or the
surrender of the right to acquire the number of shares of Common Stock
determined in accordance with Section 1.2. The Exercise Price and the number of
shares of Common Stock purchasable hereunder are subject to adjustment as
provided in Section 3 of this Warrant.

      This Warrant is subject to the following terms and conditions:

      1.    EXERCISE; ISSUANCE OF CERTIFICATES; PAYMENT FOR SHARES.

            1.1   GENERAL. This Warrant is exercisable at the option of the
holder of record hereof at any time or from time, to time, up to the Expiration
Date for all or any part of the shares of Common Stock (but not for a fraction
of a share), which may be purchased hereunder. The Company agrees that the
shares of Common Stock purchased under this Warrant shall be and are deemed to
be issued to the Holder hereof as the record owner of such shares as of the
close of

<PAGE>

business on the date on which this Warrant, properly endorsed, the completed and
executed Form of Subscription and appropriate payment for such shares shall have
each been delivered to the Company at its principal place of business.
Certificates for the shares of Common Stock so purchased, together with any
other securities or property to which the Holder is entitled upon such exercise,
shall be delivered to the Holder by the Company at the Company's expense within
a reasonable time after the rights represented by this Warrant have been so
exercised, and in any event, within five (5) business days of such exercise. In
case of a purchase of less than all the shares which may be purchased under this
Warrant, the Company shall cancel this Warrant and execute and deliver a new
Warrant or Warrants of like tenor for the balance of the shares purchasable
under the Warrant surrendered upon such purchase to the Holder hereof within a
reasonable time. Each stock certificate so delivered shall be in such
denominations of Common Stock as may be requested by the Holder hereof and shall
be registered in the name designated by such Holder.

            1.2   NET ISSUE EXERCISE. Holder agrees that it cannot "net issue
exercise" this Warrant in accordance with the provisions of this section, except
in connection with or following: (i) the Company's Initial Public Offering
(which is defined as meaning the effectiveness of the filing of the first
registration statement under the Securities Act that covers the firm
underwritten offer and sale of Common Stock by the Company to the public; and
"Securities Act" means the federal Securities Act of 1933, as amended, or any
similar federal statute and the rules and regulations of the SEC thereunder, all
as the same shall be in effect at any particular time) or (ii) an Acquisition
(as defined in Section 3.3 below) resulting in entitlement by the Holder to
acquire cash or publicly-traded securities upon exercise of this Warrant.
Notwithstanding any provisions herein to the contrary, but subject to the
restrictions in the preceding sentence, if the fair market value of one share of
the Company's Common Stock is greater than the Exercise Price (at the date of
calculation as set forth below), in lieu of exercising this Warrant for cash,
the Holder may elect a "Net Issue Exercise" pursuant to which it will receive
shares equal to the value (as determined below) of this Warrant (or the portion
thereof being exercised) by surrender of this Warrant at the principal office of
the Company together with the properly endorsed Form of Subscription and notice
of such election in which event the Company shall issue to the Holder a number
of shares of Common Stock computed using the following formula:

                      Y (A-B)
                  X = -------
                         A

      Where X = the number of shares of Common Stock to be issued to the Holder

                        Y = the number of shares of Common Stock purchasable
                        under the Warrant or, if only a portion of the Warrant
                        is being exercised, the portion of the Warrant being
                        exercised (at the date of such exercise)

                        A = the fair market value of one share of the Company's
                        Common Stock (at the date of such exercise)

                                       2.
<PAGE>

                        B = Exercise Price (as adjusted to the date of such
                        exercise).

For purposes of the above calculation, the fair market value of one share of
Common Stock shall be determined by the Company's Board of Directors in good
faith; provided, however, that where there is a public market for the Company's
Common Stock, the fair market value per share shall be the average of the
closing prices of the Company's Common Stock quoted on the Nasdaq National
Market (or similar system) or on any exchange on which the Common Stock is
listed, whichever is applicable, over the five (5) trading day period ending on
the trading day immediately preceding the day the Warrant is being exercised.

      2.    SHARES TO BE FULLY PAID; RESERVATION OF SHARES. The Company
covenants and agrees that all shares of Common Stock which may be issued upon
the exercise of the rights represented by this Warrant will, upon issuance, be
duly authorized, validly issued, fully paid and nonassessable and free from all
preemptive rights of any shareholder and free of all taxes, liens and charges
with respect to the issue thereof. The Company further covenants and agrees
that, during the period within which the rights represented by this Warrant may
be exercised, the Company will at all times have authorized and reserved, for
the purpose of issue or transfer upon exercise of the subscription rights
evidenced by this Warrant, a sufficient number of shares of authorized but
unissued Common Stock, or other securities and property, when and as required to
provide for the exercise of the rights represented by this Warrant. The Company
will take all reasonable action as may be necessary to assure that such shares
of Common Stock may be issued as provided herein without violation of any
applicable law or regulation, or of any requirements of any domestic securities
exchange upon which the Common Stock may be listed; provided, however, that the
Company shall not be required to effect a registration under Federal or State
securities laws with respect to such exercise. The Company will not take any
action which would result in any adjustment of the Exercise Price (as set forth
in Section 3 hereof) if the total number of shares of Common Stock issuable
after such action upon exercise of all outstanding warrants, together with all
shares of Common Stock then outstanding and all shares of Common Stock then
issuable upon exercise of all options and upon the conversion of all convertible
securities and other equity purchase rights then outstanding, would exceed the
total number of shares of Common Stock then authorized by the Company's
Certificate of Incorporation (the "Company Charter").

      3.    ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF SHARES. The Exercise
Price and the number of shares purchasable upon the exercise of this Warrant
shall be subject to adjustment from time to time upon the occurrence of certain
events described in this Section 3. Upon each adjustment of the Exercise Price,
the Holder of this Warrant shall thereafter be entitled to purchase, at the
Exercise Price resulting from such adjustment, the number of shares obtained by
multiplying the Exercise Price in effect immediately prior to such adjustment by
the number of shares purchasable pursuant hereto immediately prior to such
adjustment, and dividing the product thereof by the Exercise Price resulting
from such adjustment.

            3.1   SUBDIVISION OR COMBINATION OF STOCK. In case the Company shall
at any time subdivide its outstanding shares of Common Stock into a greater
number of shares, the Exercise Price in effect immediately prior to such
subdivision shall be proportionately reduced,

                                       3.
<PAGE>

and conversely, in case the outstanding shares of Common Stock of the Company
shall be combined into a smaller number of shares (by reverse stock split or
otherwise), the Exercise Price in effect immediately prior to such combination
shall be proportionately increased.

            3.2   DIVIDENDS IN COMMON STOCK, OTHER STOCK, PROPERTY,
RECLASSIFICATION. If at any time or from time to time the Holders of Common
Stock (or any shares of stock or other securities at the time receivable upon
the exercise of this Warrant) shall have received or become entitled to receive,
without payment therefor,

                  (a)   Common Stock or any shares of stock or other securities
which are at any time directly or indirectly convertible into or exchangeable
for Common Stock, or any rights or options to subscribe for, purchase or
otherwise acquire any of the foregoing by way of dividend or other distribution,

                  (b)   any cash paid or payable otherwise than as a cash
dividend, or

                  (c)   Common Stock or additional stock or other securities or
property (including cash) by way of spinoff, split-up, reclassification,
combination of shares or similar corporate rearrangement, (other than shares of
Common Stock issued as a stock split or adjustments in respect of which shall be
covered by the terms of Section 3.1 above),

then, and in each such case, the Holder hereof shall, upon the exercise of this
Warrant, be entitled to receive, in addition to the number of shares of Common
Stock receivable thereupon, and without payment of any additional consideration
therefor, the amount of stock and other securities and property (including cash
in the cases referred to in clause (b) above and this clause (c)) which such
Holder would hold on the date of such exercise had he been the holder of record
of such Common Stock as of the date on which holders of Common Stock received or
became entitled to receive such shares or all other additional stock and other
securities and property.

            3.3   ASSUMPTION ON SALE, MERGER, OR CONSOLIDATION OF THE COMPANY.

                  (a)   For the purpose of this Warrant, "Acquisition" means any
sale, assignment, transfer, exclusive license, or other disposition of all or
substantially all of the assets of the Company, or any acquisition,
reorganization, consolidation, or merger of the Company where the holders of the
Company's outstanding voting equity securities immediately prior to the
transaction beneficially own less than a majority of the outstanding equity
securities of the surviving or successor entity immediately following the
transaction.

                  (b)   The Company shall use its reasonable efforts to ensure
that upon the closing of any Acquisition (other than an Acquisition in which the
consideration received by the Company's stockholders consists solely of cash),
the successor or surviving entity shall assume the obligations of this Warrant,
and that the Warrant thereafter shall be exercisable through the Expiration Date
first set forth above for the same securities and property as would be payable
for the shares of Common Stock issuable upon exercise of the unexercised portion
of the Warrant as if such shares were outstanding on the record date for the
Acquisition and subsequent closing, subject to further adjustment from time to
time in accordance with the provisions hereof. If, notwithstanding such Company
efforts, the acquiror in an Acquisition notifies the Company

                                       4.
<PAGE>

that it shall not so assume this Warrant, then the Company shall notify the
Holder thereof within a reasonable time prior to the closing of such Acquisition
and, to the extent the Warrant shall not have been exercised or converted at or
prior to such closing, the Warrant shall terminate and be of no further force or
effect.

            3.4   NOTICES OF CHANGE. Immediately upon any adjustment in the
number or class of shares subject to this Warrant and/or of the Exercise Price,
the Company shall give written notice thereof to the Holder, setting forth in
reasonable detail and certifying the calculation of such adjustment.

      4.    ISSUE TAX. The issuance of certificates for shares of Common Stock
upon the exercise of the Warrant shall be made without charge to the Holder of
the Warrant for any issue tax (other than any applicable income taxes) in
respect thereof; provided, however, that the Company shall not be required to
pay any tax which may be payable in respect of any transfer involved in the
issuance and delivery of any certificate in a name other than that of the then
Holder of the Warrant being exercised.

      5.    CLOSING OF BOOKS. The Company will at no time close its transfer
books against the transfer of any warrant or of any shares of Common Stock
issued or issuable upon the exercise of any warrant in any manner which
interferes with the timely exercise of this Warrant (except that the Company
shall be entitled to place appropriate stop-transfer orders with respect to
transfer of securities which are subject to restrictions on transfer due to
securities laws or other legal restrictions).

      6.    NO VOTING OR DIVIDEND RIGHTS; LIMITATION OF LIABILITY. Nothing
contained in this Warrant shall be construed as conferring upon the Holder
hereof the right to vote or to consent or to receive notice as a shareholder of
the Company or any other matters or any rights whatsoever as a shareholder of
the Company. No dividends or interest shall be payable or accrued in respect of
this Warrant or the interest represented hereby or the shares purchasable
hereunder until after, and only to the extent that, this Warrant shall have been
exercised. No provisions hereof, in the absence of affirmative action by the
holder to purchase shares of Common Stock, and no mere enumeration herein of the
rights or privileges of the holder hereof, shall give rise to any liability of
such Holder for the Exercise Price or as a shareholder of the Company, whether
such liability is asserted by the Company or by its creditors.

      7.    WARRANTS TRANSFERABLE. Subject to compliance with applicable federal
and state securities laws and compliance with Section 10(c), this Warrant and
all rights hereunder are transferable, in whole or in part, without charge to
the holder hereof (except for transfer taxes), upon surrender of this Warrant
properly endorsed. Each taker and holder of this Warrant, by taking or holding
the same, consents and agrees that the Company, at the Company's option, may
treat the holder hereof registered on the books of the Company as the absolute
owner hereof for all purposes and as the person entitled to exercise the rights
represented by this Warrant notwithstanding any notice to the contrary. By its
acceptance of transfer of this Warrant, any transferee of this Warrant shall be
deemed to have made the representations and warranties set forth in Section 10
below.

                                       5.
<PAGE>

      8.    RIGHTS AND OBLIGATIONS SURVIVE EXERCISE OF WARRANT. The rights and
obligations of the Company, of the holder of this Warrant and of the holder of
shares of Common Stock issued upon exercise of this Warrant, shall survive the
exercise of this Warrant.

      9.    FURTHER REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE COMPANY.

                  (a)   DUE AUTHORITY. The execution and delivery by the Company
of this Warrant and the performance of all obligations of the Company hereunder,
including the issuance to Holder of the right to acquire the shares of Common
Stock, have been duly authorized by all necessary corporate action on the part
of the Company, and the Warrant is not inconsistent with the Company Charter or
Bylaws and constitutes a legal, valid and binding agreement of the Company,
enforceable in accordance with its terms.

                  (b)   CONSENTS AND APPROVALS. No consent or approval of,
giving of notice to, registration with, or taking of any other action in respect
of any state, federal or other governmental authority or agency is required with
respect to the execution, delivery and performance by the Company of its
obligations under this Warrant, except for any filing required by applicable
federal and state securities laws, which filing will be effective by the time
required thereby.

                  (c)   EXEMPT TRANSACTION. Subject to the accuracy of the
Holders representations in Section 10 hereof, the issuance of the Common Stock
upon exercise of this Warrant will constitute a transaction exempt from the
registration requirements of Section 5 of the Securities Act of 1933, as amended
(the "1933 ACT"), in reliance upon Section 4(2) thereof.

      10.   REPRESENTATIONS AND COVENANTS OF THE HOLDER.

      This Warrant has been entered into by the Company in reliance upon the
following representations and covenants of the Holder, as of the date hereof, as
of the date of any transfer or assignment hereof, and as of the date of any
exercise of this Warrant:

                  (a)   INVESTMENT PURPOSE. The Warrant and the Common Stock
issuable upon exercise of the Warrant will be acquired for investment and not
with a view to the sale or distribution of any part thereof, and the Holder has
no present intention of selling or engaging in any public distribution of the
same except pursuant to a registration or exemption pursuant to the 1933 Act.

                  (b)   PRIVATE ISSUE. The Holder understands (i) that the
Warrant and the Common Stock issuable upon exercise of this Warrant is not
registered under the 1933 Act or qualified under applicable state securities
laws on the ground that the issuance contemplated by this Warrant will be exempt
from the registration and qualifications requirements thereof pursuant to
Section 4(2) of the 1933 Act and any applicable state securities laws, and (ii)
that the Company's reliance on such exemption is predicated on the
representations set forth in this Section 10.

                                       6.
<PAGE>

                  (c)   DISPOSITION OF HOLDERS RIGHTS. In no event will the
Holder make a disposition of the Warrant or the Common Stock issuable upon
exercise of the Warrant unless and until (i) it shall have notified the Company
of the proposed disposition, and (ii) if requested by the Company, it shall have
furnished the Company with an opinion of counsel (which counsel may either be
inside or outside counsel to the Holder) satisfactory to the Company and its
counsel to the effect that (A) appropriate action necessary for compliance with
the 1933 Act has been taken, or (B) an exemption from the registration
requirements of the 1933 Act is available and (iii) the recipient of such
Warrant or Common Stock is able to make the representations and warranties in
Section 10 of this Warrant as of the date of such disposition. Notwithstanding
the foregoing, the restrictions imposed upon the transferability of any of its
rights to acquire Common Stock or Common Stock issuable on the exercise of such
rights shall terminate as to any particular share of Common Stock when (1) such
security shall have been effectively registered under the 1933 Act and sold by
the holder thereof in accordance with such registration or (2) a letter shall
have been issued to the Holder at its request by the staff of the Securities and
Exchange Commission or a ruling shall have been issued to the Holder at its
request by such Commission stating that no action shall be recommended by such
staff or taken by such Commission, as the case may be, if such security is
transferred without registration under the 1933 Act in accordance with the
conditions set forth in such letter or ruling and such letter or ruling
specifies that no subsequent restrictions on transfer are required. In addition
to the foregoing, prior to the Company's Initial Public Offering, Holder shall
not, without the prior written consent of the Company, transfer the Warrant (or
any part hereof), any Common Stock issuable or issued upon exercise of the
Warrant, or any securities issued or issuable upon conversion of the Common
Stock, to any person who directly competes with the Company, unless such
transfer is in connection with an acquisition of the Company by any such person.

                  (d)   FINANCIAL RISK. The Holder has such knowledge and
experience in financial and business matters as to be capable of evaluating the
merits and risks of its investment, and has the ability to bear the economic
risks of its investment.

                  (e)   RISK OF NO REGISTRATION. The Holder understands that if
the Company does not register with the Securities and Exchange Commission
pursuant to Section 12 of the 1933 Act, or file reports pursuant to Section
15(d), of the Securities Exchange Act of 1934 (the "1934 ACT"), or if a
registration statement covering the securities under the 1933 Act is not in
effect when it desires to sell (i) the Warrant, or (ii) any Common Stock
issuable upon exercise of the Warrant, it may be required to hold such
securities for an indefinite period. The Holder also understands that any sale
of the Warrant or the Common Stock issuable upon exercise of the Warrant which
might be made by it in reliance upon Rule 144 under the 1933 Act may be made
only in accordance with the terms and conditions of that Rule.

                  (f)   ACCREDITED INVESTOR. Holder is an "ACCREDITED INVESTOR"
within the meaning of Rule 501 of Regulation D under the 1933 Act, as presently
in effect.

      11.   LOCKUP. If so requested in writing by the underwriters for the
Initial Public Offering of securities of the Company, each holder of this
Warrant or any securities of the Company issued or issuable in connection with
the exercise of this Warrant hereby agree that such holders shall not sell or
transfer any such securities (other than securities being registered in

                                       7.
<PAGE>

such offering), without the consent of such underwriters, for a period of not
more than 180 days following the effective date of the registration statement
relating to such offering.

      12.   RESTRICTIVE LEGEND. Except as otherwise expressly provided below,
this Warrant and each successor or replacement Warrant shall bear the legend set
forth above, and each certificate representing the securities issued upon
exercise of this Warrant shall be stamped or otherwise imprinted with a legend
substantially in the following form (and any other legend required by state
securities or corporate law):

      "The securities represented by this certificate have not been
      registered under the Securities Act of 1933 or applicable state
      securities laws. These securities have been acquired for
      investment and not with a view to distribution or resale, and may
      not be sold, mortgaged, pledged, hypothecated or otherwise
      transferred without an effective registration statement for such
      securities under the Securities Act of 1933 and applicable state
      securities laws, or the availability of an exemption from the
      registration provisions of the Securities Act of 1933 and
      applicable state securities laws. Transfer of these securities is
      subject to the terms of a Warrant effective February 2, 2004 under
      which these securities were acquired."

Whenever the restrictions referred to in the legend shall terminate, as provided
in Section 10(c), the Holder or holder of a share of Common Stock then
outstanding as to which such restrictions have terminated shall be entitled to
receive from the Company, without expense to such holder, one or more new
certificates for the Warrant or for such shares of Common Stock not bearing such
restrictive legend.

      13.   MODIFICATION AND WAIVER. This Warrant and any provision hereof may
be changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

      14.   NOTICES. Any notice, request or other document required or permitted
to be given or delivered to the holder hereof or the Company shall be delivered
or shall be sent by an established overnight service provider (e.g., Federal
Express), or registered or certified mail, postage prepaid, to each such holder
at its address as shown on the books of the Company or to the Company at the
address indicated therefor in the first paragraph of this Warrant or such other
address as either may from time to time provide to the other in accordance with
this Section.

      15.   BINDING EFFECT ON SUCCESSORS. This Warrant shall be binding upon any
corporation succeeding the Company by merger, consolidation or acquisition of
all or substantially all of the Company's assets. All of the obligations of the
Company relating to the Common Stock issuable upon the exercise of this Warrant
shall survive the exercise and termination of this Warrant. All of the covenants
and agreements of the Company shall inure to the benefit of the successors and
assigns of the holder hereof.

      16.   DESCRIPTIVE HEADINGS AND GOVERNING LAW. The description headings of
the several sections and paragraphs of this Warrant are inserted for convenience
only and do not

                                       8.
<PAGE>

constitute a part of this Warrant. This Warrant shall be construed and enforced
in accordance with, and the rights of the parties shall be governed by, the laws
of the Delaware, without giving effect to principles of conflicts of laws.

      17.   LOST WARRANTS. The Company represents and warrants to the Holder
hereof that upon receipt of evidence reasonably satisfactory to the Company of
the loss, theft, destruction, or mutilation of this Warrant and, in the case of
any such loss, theft or destruction, upon receipt of an indemnity reasonably
satisfactory to the Company, or in the case of any such mutilation upon
surrender and cancellation of such Warrant, the Company, at its expense, will
make and deliver a new Warrant, of like tenor, in lieu of the lost, stolen,
destroyed or mutilated Warrant.

      18.   FRACTIONAL SHARES. No fractional shares shall be issued upon
exercise of this Warrant. The Company shall, in lieu of issuing any fractional
share, pay the holder entitled to such fraction a sum in cash equal to such
fraction multiplied by the then effective Exercise Price.

                                       9.
<PAGE>

      IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed by its officers, thereunto duly authorized.

                                            EGENERA, INC.
                                            a Delaware corporation

                                            By: /s/ T. Sheehan
                                                ----------------------------

                                            Name: Thomas F. Sheehan

                                            Title: Chief Financial Officer

ATTEST:

/s/ illegible
------------------------

Asst. Secretary